A Giava, corda di divisione è un'operazione importante e solitamente utilizzata durante la codifica. Java offre diversi modi per dividere la corda . Ma il modo più comune è utilizzare il file metodo split() della classe String. In questa sezione impareremo come dividere una stringa in Java con delimitatore. Insieme a questo, impareremo anche altri metodi per dividere la stringa, come l'uso della classe StringTokenizer, Metodo Scanner.useDelimiter() . Prima di passare all'argomento, capiamo cos'è il delimitatore.
Cos'è un delimitatore?
In Giava , Delimitatori sono i caratteri che dividono (separano) la stringa in token. Java ci consente di definire qualsiasi carattere come delimitatore. Esistono molti metodi di suddivisione delle stringhe forniti da Java che utilizzano il carattere di spazio bianco come delimitatore. IL delimitatore di spazi bianchi è il delimitatore predefinito a Giava.
Prima di passare al programma, comprendiamo il concetto di stringa.
La stringa è composta da due tipi di testo che sono gettoni E Delimitatori. I token sono le parole significative e i delimitatori sono i caratteri che dividono o separano i token. Capiamolo attraverso un esempio.
Per comprendere il delimitatore in Java , dobbiamo amichevole con il Espressione regolare Java . È necessario quando il delimitatore viene utilizzato come carattere speciale nelle espressioni regolari, come (.) e (|).
Esempio di delimitatore
Corda: Javatpoint è il miglior sito web per apprendere nuove tecnologie.
Nella stringa sopra, i token sono, Javatpoint è il miglior sito web per apprendere nuove tecnologie e i delimitatori sono spazi bianchi tra i due gettoni.
Come dividere una stringa in Java con delimitatore?
Java fornisce il seguente modo per dividere una stringa in token:
- Utilizzo del metodo Scanner.next()
- Utilizzando il metodo String.split()
- Utilizzo della classe StringTokenizer
Utilizzo del metodo Scanner.next()
È il metodo della classe Scanner. Trova e restituisce il token successivo dallo scanner. Divide la stringa in token in base al delimitatore di spazi bianchi. Il token completo viene identificato dall'input che corrisponde al modello di delimitatore.
Sintassi:
public String next();
Lancia NoSuchElementException se il token successivo non è disponibile. Lancia anche IllegalStateException se lo scanner di input è chiuso.
Creiamo un programma che divide un oggetto stringa utilizzando il metodo next() che utilizza gli spazi bianchi per dividere la stringa in token.
SplitStringEsempio1.java
import java.util.Scanner; public class SplitStringExample1 { public static void main(String[] args) { //declaring a string String str='Javatpoint is the best website to learn new technologies'; //constructor of the Scanner class Scanner sc=new Scanner(str); while (sc.hasNext()) { //invoking next() method that splits the string String tokens=sc.next(); //prints the separated tokens System.out.println(tokens); //closing the scanner sc.close(); } } } Produzione:
formato.stringa
Javatpoint is the best website to learn new technologies
Nel programma sopra riportato è da notare che nel costruttore della classe Scanner invece di passare il System.in abbiamo passato una variabile stringa str. Lo abbiamo fatto perché prima di manipolare la stringa, dobbiamo leggerla.
Utilizzando il metodo String.split()
IL diviso() metodo del Corda classe viene utilizzato per dividere una stringa in una matrice di oggetti String in base al delimitatore specificato che corrisponde all'espressione regolare. Consideriamo ad esempio la seguente stringa:
String str= 'Welcome,to,the,word,of,technology';
La stringa precedente è separata da virgole. Possiamo dividere la stringa sopra usando la seguente espressione:
String[] tokens=s.split(',');
L'espressione precedente divide la stringa in token quando i token sono separati dal carattere delimitatore specificato virgola (,). La stringa specificata è suddivisa nei seguenti oggetti stringa:
Welcome to the word of technology
Esistono due varianti dei metodi split():
- dividere (stringa regex)
- split(String regex, limite int)
String.split(Regex di stringa)
Divide la stringa in base alla regex dell'espressione regolare specificata. Possiamo usare un punto (.), uno spazio ( ), una virgola (,) e qualsiasi carattere (come z, a, g, l, ecc.)
Sintassi:
public String[] split(String regex)
Il metodo analizza un'espressione regolare delimitatrice come argomento. Restituisce un array di oggetti String. Lancia PatternSyntaxException se l'espressione regolare analizzata ha una sintassi non valida.
Usiamo il metodo split() e dividiamo la stringa con una virgola.
SplitStringEsempio2.java
public class SplitStringExample2 { public static void main(String args[]) { //defining a String object String s = 'Life,is,your,creation'; //split string delimited by comma String[] stringarray = s.split(','); //we can use dot, whitespace, any character //iterate over string array for(int i=0; i<stringarray.length; i++) { prints the tokens system.out.println(stringarray[i]); } < pre> <p> <strong>Output:</strong> </p> <pre> Life is your creation </pre> <p>In the above example, the string object is delimited by a comma. The split() method splits the string when it finds the comma as a delimiter.</p> <p>Let's see another example in which we will use multiple delimiters to split the string.</p> <p> <strong>SplitStringExample3.java</strong> </p> <pre> public class SplitStringExample3 { public static void main(String args[]) { //defining a String object String s = 'If you don't like something, change.it.'; //split string by multiple delimiters String[] stringarray = s.split('[, . ']+'); //iterate over string array for(int i=0; i<stringarray.length; i++) { prints the tokens system.out.println(stringarray[i]); } < pre> <p> <strong>Output:</strong> </p> <pre> If you don t like something change it </pre> <p> <strong>String.split(String regex, int limit)</strong> </p> <p>It allows us to split string specified by delimiter but into a limited number of tokens. The method accepts two parameters regex (a delimiting regular expression) and limit. The limit parameter is used to control the number of times the pattern is applied that affects the resultant array. It returns an array of String objects computed by splitting the given string according to the limit parameter.</p> <p>There is a slight difference between the variant of the split() methods that it limits the number of tokens returned after invoking the method.</p> <p> <strong>Syntax:</strong> </p> <pre> public String[] split(String regex, int limit) </pre> <p>It throws <strong>PatternSyntaxException</strong> if the parsed regular expression has an invalid syntax.</p> <p>The limit parameter may be positive, negative, or equal to the limit.</p> <p> <strong>SplitStringExample4.java</strong> </p> <pre> public class SplitStringExample4 { public static void main(String args[]) { String str1 = '468-567-7388'; String str2 = 'Life,is,your,creation'; String str3 = 'Hello! how are you?'; String[] stringarray1 = str1.split('8',2); System.out.println('When the limit is positive:'); System.out.println('Number of tokens: '+stringarray1.length); for(int i=0; i<stringarray1.length; i++) { system.out.println(stringarray1[i]); } string[] stringarray2="str2.split('y',-3);" system.out.println('
when the limit is negative: '); system.out.println('number of tokens: '+stringarray2.length); for(int i="0;" i<stringarray2.length; system.out.println(stringarray2[i]); stringarray3="str3.split('!',0);" equal to 0:'); '+stringarray3.length); i<stringarray3.length; system.out.println(stringarray3[i]); < pre> <p> <strong>Output:</strong> </p> <pre> When the limit is positive: Number of tokens: 2 46 -567-7388 When the limit is negative: Number of tokens: 2 Life,is, our,creation When the limit is equal to 0: Number of tokens: 2 Hello how are you? </pre> <p>In the above code snippet, we see that:</p> <ul> <li>When the limit is 2, the number of tokens in the string array is two.</li> <li>When the limit is -3, the specified string is split into 2 tokens. It includes the trailing spaces.</li> <li>When the limit is 0, the specified string is split into 2 tokens. In this case, trailing space is omitted.</li> </ul> <h3>Example of Pipe Delimited String</h3> <p>Splitting a string delimited by pipe (|) is a little bit tricky. Because the pipe is a special character in Java regular expression.</p> <p>Let's create a string delimited by pipe and split it by pipe.</p> <p> <strong>SplitStringExample5.java</strong> </p> <pre> public class SplitStringExample5 { public static void main(String args[]) { //defining a String object String s = 'Life|is|your|creation'; //split string delimited by comma String[] stringarray = s.split('|'); //we can use dot, whitespace, any character //iterate over string array for(int i=0; i<stringarray.length; i++) { prints the tokens system.out.println(stringarray[i]); } < pre> <p> <strong>Output:</strong> </p> <pre> L i f e | i s | y o u r | c r e a t i o n </pre> <p>In the above example, we see that it does not produce the same output as other delimiter yields. It should produce an array of tokens, <strong>life, yours,</strong> and <strong>creation</strong> , but it is not. It gives the result, as we have seen in the output above.</p> <p>The reason behind it that the regular expression engine interprets the pipe delimiter as a <strong>Logical OR operator</strong> . The regex engine splits the String on empty String.</p> <p>In order to resolve this problem, we must <strong>escape</strong> the pipe character when passed to the split() method. We use the following statement to escape the pipe character:</p> <pre> String[] stringarray = s.split('\|'); </pre> <p>Add a pair of <strong>backslash (\)</strong> before the delimiter to escape the pipe. After doing the changes in the above program, the regex engine interprets the pipe character as a delimiter.</p> <p>Another way to escape the pipe character is to put the pipe character inside a pair of square brackets, as shown below. In the Java regex API, the pair of square brackets act as a character class.</p> <pre> String[] stringarray = s.split('[|]'); </pre> <p>Both the above statements yield the following output:</p> <p> <strong>Output:</strong> </p> <pre> Life is your creation </pre> <h3>Using StringTokenizer Class</h3> <p>Java <strong>StringTokenizer</strong> is a legacy class that is defined in java.util package. It allows us to split the string into tokens. It is not used by the programmer because the split() method of the String class does the same work. So, the programmer prefers the split() method instead of the StringTokenizer class. We use the following two methods of the class:</p> <p> <strong>StringTokenizer.hasMoreTokens()</strong> </p> <p>The method iterates over the string and checks if there are more tokens available in the tokenizer string. It returns true if there is one token is available in the string after the current position, else returns false. It internally calls the <strong>nextToken()</strong> method if it returns true and the nextToken() method returns the token.</p> <p> <strong>Syntax:</strong> </p> <pre> public boolean hasMoreTokens() </pre> <p> <strong>StringTokenizer.nextToken()</strong> </p> <p>It returns the next token from the string tokenizer. It throws <strong>NoSuchElementException</strong> if the tokens are not available in the string tokenizer.</p> <p> <strong>Syntax:</strong> </p> <pre> public String nextToken() </pre> <p>Let's create a program that splits the string using the StringTokenizer class.</p> <p> <strong>SplitStringExample6.java</strong> </p> <pre> import java.util.StringTokenizer; public class SplitStringExample6 { public static void main(String[] args) { //defining a String object String str = 'Welcome/to/Javatpoint'; //constructor of the StringTokenizer class StringTokenizer tokens = new StringTokenizer(str, '/'); //checks if the string has more tokens or not while (tokens.hasMoreTokens()) { //prints the tokens System.out.println(tokens.nextToken()); } } } </pre> <p> <strong>Output:</strong> </p> <pre> Welcome to Javatpoint </pre> <h2>Using Scanner.useDelimiter() Method</h2> <p>Java <strong>Scanner</strong> class provides the <strong>useDelimiter()</strong> method to split the string into tokens. There are two variants of the useDelimiter() method:</p> <ul> <li>useDelimiter(Pattern pattern)</li> <li>useDelimiter(String pattern)</li> </ul> <h3>useDelimiter(Pattern pattern)</h3> <p>The method sets the scanner's delimiting pattern to the specified string. It parses a delimiting pattern as an argument. It returns the Scanner.</p> <p> <strong>Syntax:</strong> </p> <pre> public Scanner useDelimiter(Pattern pattern) </pre> <h3>useDelimiter(String pattern)</h3> <p>The method sets the scanner's delimiting pattern to a pattern that constructs from the specified string. It parses a delimiting pattern as an argument. It returns the Scanner.</p> <p> <strong>Syntax:</strong> </p> <pre> public Scanner useDelimiter(String pattern) </pre> <h4>Note: Both the above methods behave in the same way, as invoke the useDelimiter(Pattern.compile(pattern)).</h4> <p>In the following program, we have used the useDelimiter() method to split the string.</p> <p> <strong>SplitStringExample7.java</strong> </p> <pre> import java.util.Scanner; public class SplitStringExample7 { public static void main(String args[]) { //construtor of the Scanner class Scanner scan = new Scanner('Do/your/work/self'); //Initialize the string delimiter scan.useDelimiter('/'); //checks if the tokenized Strings has next token while(scan.hasNext()) { //prints the next token System.out.println(scan.next()); } //closing the scanner scan.close(); } } </pre> <p> <strong>Output:</strong> </p> <pre> Do your work self </pre> <hr></stringarray.length;></pre></stringarray1.length;></pre></stringarray.length;></pre></stringarray.length;> Nell'esempio precedente, l'oggetto stringa è delimitato da una virgola. Il metodo split() divide la stringa quando trova la virgola come delimitatore.
Vediamo un altro esempio in cui utilizzeremo più delimitatori per dividere la stringa.
SplitStringEsempio3.java
public class SplitStringExample3 { public static void main(String args[]) { //defining a String object String s = 'If you don't like something, change.it.'; //split string by multiple delimiters String[] stringarray = s.split('[, . ']+'); //iterate over string array for(int i=0; i<stringarray.length; i++) { prints the tokens system.out.println(stringarray[i]); } < pre> <p> <strong>Output:</strong> </p> <pre> If you don t like something change it </pre> <p> <strong>String.split(String regex, int limit)</strong> </p> <p>It allows us to split string specified by delimiter but into a limited number of tokens. The method accepts two parameters regex (a delimiting regular expression) and limit. The limit parameter is used to control the number of times the pattern is applied that affects the resultant array. It returns an array of String objects computed by splitting the given string according to the limit parameter.</p> <p>There is a slight difference between the variant of the split() methods that it limits the number of tokens returned after invoking the method.</p> <p> <strong>Syntax:</strong> </p> <pre> public String[] split(String regex, int limit) </pre> <p>It throws <strong>PatternSyntaxException</strong> if the parsed regular expression has an invalid syntax.</p> <p>The limit parameter may be positive, negative, or equal to the limit.</p> <p> <strong>SplitStringExample4.java</strong> </p> <pre> public class SplitStringExample4 { public static void main(String args[]) { String str1 = '468-567-7388'; String str2 = 'Life,is,your,creation'; String str3 = 'Hello! how are you?'; String[] stringarray1 = str1.split('8',2); System.out.println('When the limit is positive:'); System.out.println('Number of tokens: '+stringarray1.length); for(int i=0; i<stringarray1.length; i++) { system.out.println(stringarray1[i]); } string[] stringarray2="str2.split('y',-3);" system.out.println(\'
when the limit is negative: \'); system.out.println(\'number of tokens: \'+stringarray2.length); for(int i="0;" i<stringarray2.length; system.out.println(stringarray2[i]); stringarray3="str3.split('!',0);" equal to 0:\'); \'+stringarray3.length); i<stringarray3.length; system.out.println(stringarray3[i]); < pre> <p> <strong>Output:</strong> </p> <pre> When the limit is positive: Number of tokens: 2 46 -567-7388 When the limit is negative: Number of tokens: 2 Life,is, our,creation When the limit is equal to 0: Number of tokens: 2 Hello how are you? </pre> <p>In the above code snippet, we see that:</p> <ul> <li>When the limit is 2, the number of tokens in the string array is two.</li> <li>When the limit is -3, the specified string is split into 2 tokens. It includes the trailing spaces.</li> <li>When the limit is 0, the specified string is split into 2 tokens. In this case, trailing space is omitted.</li> </ul> <h3>Example of Pipe Delimited String</h3> <p>Splitting a string delimited by pipe (|) is a little bit tricky. Because the pipe is a special character in Java regular expression.</p> <p>Let's create a string delimited by pipe and split it by pipe.</p> <p> <strong>SplitStringExample5.java</strong> </p> <pre> public class SplitStringExample5 { public static void main(String args[]) { //defining a String object String s = 'Life|is|your|creation'; //split string delimited by comma String[] stringarray = s.split('|'); //we can use dot, whitespace, any character //iterate over string array for(int i=0; i<stringarray.length; i++) { prints the tokens system.out.println(stringarray[i]); } < pre> <p> <strong>Output:</strong> </p> <pre> L i f e | i s | y o u r | c r e a t i o n </pre> <p>In the above example, we see that it does not produce the same output as other delimiter yields. It should produce an array of tokens, <strong>life, yours,</strong> and <strong>creation</strong> , but it is not. It gives the result, as we have seen in the output above.</p> <p>The reason behind it that the regular expression engine interprets the pipe delimiter as a <strong>Logical OR operator</strong> . The regex engine splits the String on empty String.</p> <p>In order to resolve this problem, we must <strong>escape</strong> the pipe character when passed to the split() method. We use the following statement to escape the pipe character:</p> <pre> String[] stringarray = s.split('\|'); </pre> <p>Add a pair of <strong>backslash (\)</strong> before the delimiter to escape the pipe. After doing the changes in the above program, the regex engine interprets the pipe character as a delimiter.</p> <p>Another way to escape the pipe character is to put the pipe character inside a pair of square brackets, as shown below. In the Java regex API, the pair of square brackets act as a character class.</p> <pre> String[] stringarray = s.split('[|]'); </pre> <p>Both the above statements yield the following output:</p> <p> <strong>Output:</strong> </p> <pre> Life is your creation </pre> <h3>Using StringTokenizer Class</h3> <p>Java <strong>StringTokenizer</strong> is a legacy class that is defined in java.util package. It allows us to split the string into tokens. It is not used by the programmer because the split() method of the String class does the same work. So, the programmer prefers the split() method instead of the StringTokenizer class. We use the following two methods of the class:</p> <p> <strong>StringTokenizer.hasMoreTokens()</strong> </p> <p>The method iterates over the string and checks if there are more tokens available in the tokenizer string. It returns true if there is one token is available in the string after the current position, else returns false. It internally calls the <strong>nextToken()</strong> method if it returns true and the nextToken() method returns the token.</p> <p> <strong>Syntax:</strong> </p> <pre> public boolean hasMoreTokens() </pre> <p> <strong>StringTokenizer.nextToken()</strong> </p> <p>It returns the next token from the string tokenizer. It throws <strong>NoSuchElementException</strong> if the tokens are not available in the string tokenizer.</p> <p> <strong>Syntax:</strong> </p> <pre> public String nextToken() </pre> <p>Let's create a program that splits the string using the StringTokenizer class.</p> <p> <strong>SplitStringExample6.java</strong> </p> <pre> import java.util.StringTokenizer; public class SplitStringExample6 { public static void main(String[] args) { //defining a String object String str = 'Welcome/to/Javatpoint'; //constructor of the StringTokenizer class StringTokenizer tokens = new StringTokenizer(str, '/'); //checks if the string has more tokens or not while (tokens.hasMoreTokens()) { //prints the tokens System.out.println(tokens.nextToken()); } } } </pre> <p> <strong>Output:</strong> </p> <pre> Welcome to Javatpoint </pre> <h2>Using Scanner.useDelimiter() Method</h2> <p>Java <strong>Scanner</strong> class provides the <strong>useDelimiter()</strong> method to split the string into tokens. There are two variants of the useDelimiter() method:</p> <ul> <li>useDelimiter(Pattern pattern)</li> <li>useDelimiter(String pattern)</li> </ul> <h3>useDelimiter(Pattern pattern)</h3> <p>The method sets the scanner's delimiting pattern to the specified string. It parses a delimiting pattern as an argument. It returns the Scanner.</p> <p> <strong>Syntax:</strong> </p> <pre> public Scanner useDelimiter(Pattern pattern) </pre> <h3>useDelimiter(String pattern)</h3> <p>The method sets the scanner's delimiting pattern to a pattern that constructs from the specified string. It parses a delimiting pattern as an argument. It returns the Scanner.</p> <p> <strong>Syntax:</strong> </p> <pre> public Scanner useDelimiter(String pattern) </pre> <h4>Note: Both the above methods behave in the same way, as invoke the useDelimiter(Pattern.compile(pattern)).</h4> <p>In the following program, we have used the useDelimiter() method to split the string.</p> <p> <strong>SplitStringExample7.java</strong> </p> <pre> import java.util.Scanner; public class SplitStringExample7 { public static void main(String args[]) { //construtor of the Scanner class Scanner scan = new Scanner('Do/your/work/self'); //Initialize the string delimiter scan.useDelimiter('/'); //checks if the tokenized Strings has next token while(scan.hasNext()) { //prints the next token System.out.println(scan.next()); } //closing the scanner scan.close(); } } </pre> <p> <strong>Output:</strong> </p> <pre> Do your work self </pre> <hr></stringarray.length;></pre></stringarray1.length;></pre></stringarray.length;> String.split(String regex, limite int)
Ci consente di dividere la stringa specificata dal delimitatore ma in un numero limitato di token. Il metodo accetta due parametri regex (un'espressione regolare di delimitazione) e limit. Il parametro limit viene utilizzato per controllare il numero di volte in cui viene applicato il modello che influisce sull'array risultante. Restituisce un array di oggetti String calcolati dividendo la stringa data in base al parametro limit.
C'è una leggera differenza tra la variante dei metodi split() che limita il numero di token restituiti dopo aver invocato il metodo.
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Sintassi:
public String[] split(String regex, int limit)
Lancia PatternSyntaxException se l'espressione regolare analizzata ha una sintassi non valida.
Il parametro limite può essere positivo, negativo o uguale al limite.
SplitStringExample4.java
public class SplitStringExample4 { public static void main(String args[]) { String str1 = '468-567-7388'; String str2 = 'Life,is,your,creation'; String str3 = 'Hello! how are you?'; String[] stringarray1 = str1.split('8',2); System.out.println('When the limit is positive:'); System.out.println('Number of tokens: '+stringarray1.length); for(int i=0; i<stringarray1.length; i++) { system.out.println(stringarray1[i]); } string[] stringarray2="str2.split('y',-3);" system.out.println(\'
when the limit is negative: \'); system.out.println(\'number of tokens: \'+stringarray2.length); for(int i="0;" i<stringarray2.length; system.out.println(stringarray2[i]); stringarray3="str3.split('!',0);" equal to 0:\'); \'+stringarray3.length); i<stringarray3.length; system.out.println(stringarray3[i]); < pre> <p> <strong>Output:</strong> </p> <pre> When the limit is positive: Number of tokens: 2 46 -567-7388 When the limit is negative: Number of tokens: 2 Life,is, our,creation When the limit is equal to 0: Number of tokens: 2 Hello how are you? </pre> <p>In the above code snippet, we see that:</p> <ul> <li>When the limit is 2, the number of tokens in the string array is two.</li> <li>When the limit is -3, the specified string is split into 2 tokens. It includes the trailing spaces.</li> <li>When the limit is 0, the specified string is split into 2 tokens. In this case, trailing space is omitted.</li> </ul> <h3>Example of Pipe Delimited String</h3> <p>Splitting a string delimited by pipe (|) is a little bit tricky. Because the pipe is a special character in Java regular expression.</p> <p>Let's create a string delimited by pipe and split it by pipe.</p> <p> <strong>SplitStringExample5.java</strong> </p> <pre> public class SplitStringExample5 { public static void main(String args[]) { //defining a String object String s = 'Life|is|your|creation'; //split string delimited by comma String[] stringarray = s.split('|'); //we can use dot, whitespace, any character //iterate over string array for(int i=0; i<stringarray.length; i++) { prints the tokens system.out.println(stringarray[i]); } < pre> <p> <strong>Output:</strong> </p> <pre> L i f e | i s | y o u r | c r e a t i o n </pre> <p>In the above example, we see that it does not produce the same output as other delimiter yields. It should produce an array of tokens, <strong>life, yours,</strong> and <strong>creation</strong> , but it is not. It gives the result, as we have seen in the output above.</p> <p>The reason behind it that the regular expression engine interprets the pipe delimiter as a <strong>Logical OR operator</strong> . The regex engine splits the String on empty String.</p> <p>In order to resolve this problem, we must <strong>escape</strong> the pipe character when passed to the split() method. We use the following statement to escape the pipe character:</p> <pre> String[] stringarray = s.split('\|'); </pre> <p>Add a pair of <strong>backslash (\)</strong> before the delimiter to escape the pipe. After doing the changes in the above program, the regex engine interprets the pipe character as a delimiter.</p> <p>Another way to escape the pipe character is to put the pipe character inside a pair of square brackets, as shown below. In the Java regex API, the pair of square brackets act as a character class.</p> <pre> String[] stringarray = s.split('[|]'); </pre> <p>Both the above statements yield the following output:</p> <p> <strong>Output:</strong> </p> <pre> Life is your creation </pre> <h3>Using StringTokenizer Class</h3> <p>Java <strong>StringTokenizer</strong> is a legacy class that is defined in java.util package. It allows us to split the string into tokens. It is not used by the programmer because the split() method of the String class does the same work. So, the programmer prefers the split() method instead of the StringTokenizer class. We use the following two methods of the class:</p> <p> <strong>StringTokenizer.hasMoreTokens()</strong> </p> <p>The method iterates over the string and checks if there are more tokens available in the tokenizer string. It returns true if there is one token is available in the string after the current position, else returns false. It internally calls the <strong>nextToken()</strong> method if it returns true and the nextToken() method returns the token.</p> <p> <strong>Syntax:</strong> </p> <pre> public boolean hasMoreTokens() </pre> <p> <strong>StringTokenizer.nextToken()</strong> </p> <p>It returns the next token from the string tokenizer. It throws <strong>NoSuchElementException</strong> if the tokens are not available in the string tokenizer.</p> <p> <strong>Syntax:</strong> </p> <pre> public String nextToken() </pre> <p>Let's create a program that splits the string using the StringTokenizer class.</p> <p> <strong>SplitStringExample6.java</strong> </p> <pre> import java.util.StringTokenizer; public class SplitStringExample6 { public static void main(String[] args) { //defining a String object String str = 'Welcome/to/Javatpoint'; //constructor of the StringTokenizer class StringTokenizer tokens = new StringTokenizer(str, '/'); //checks if the string has more tokens or not while (tokens.hasMoreTokens()) { //prints the tokens System.out.println(tokens.nextToken()); } } } </pre> <p> <strong>Output:</strong> </p> <pre> Welcome to Javatpoint </pre> <h2>Using Scanner.useDelimiter() Method</h2> <p>Java <strong>Scanner</strong> class provides the <strong>useDelimiter()</strong> method to split the string into tokens. There are two variants of the useDelimiter() method:</p> <ul> <li>useDelimiter(Pattern pattern)</li> <li>useDelimiter(String pattern)</li> </ul> <h3>useDelimiter(Pattern pattern)</h3> <p>The method sets the scanner's delimiting pattern to the specified string. It parses a delimiting pattern as an argument. It returns the Scanner.</p> <p> <strong>Syntax:</strong> </p> <pre> public Scanner useDelimiter(Pattern pattern) </pre> <h3>useDelimiter(String pattern)</h3> <p>The method sets the scanner's delimiting pattern to a pattern that constructs from the specified string. It parses a delimiting pattern as an argument. It returns the Scanner.</p> <p> <strong>Syntax:</strong> </p> <pre> public Scanner useDelimiter(String pattern) </pre> <h4>Note: Both the above methods behave in the same way, as invoke the useDelimiter(Pattern.compile(pattern)).</h4> <p>In the following program, we have used the useDelimiter() method to split the string.</p> <p> <strong>SplitStringExample7.java</strong> </p> <pre> import java.util.Scanner; public class SplitStringExample7 { public static void main(String args[]) { //construtor of the Scanner class Scanner scan = new Scanner('Do/your/work/self'); //Initialize the string delimiter scan.useDelimiter('/'); //checks if the tokenized Strings has next token while(scan.hasNext()) { //prints the next token System.out.println(scan.next()); } //closing the scanner scan.close(); } } </pre> <p> <strong>Output:</strong> </p> <pre> Do your work self </pre> <hr></stringarray.length;></pre></stringarray1.length;> Nello snippet di codice sopra, vediamo che:
- Quando il limite è 2, il numero di token nell'array di stringhe è due.
- Quando il limite è -3, la stringa specificata viene divisa in 2 token. Include gli spazi finali.
- Quando il limite è 0, la stringa specificata viene divisa in 2 token. In questo caso, lo spazio finale viene omesso.
Esempio di stringa delimitata da pipe
Dividere una stringa delimitata da una barra verticale (|) è un po' complicata. Perché la pipe è un carattere speciale nell'espressione regolare Java.
Creiamo una stringa delimitata da pipe e dividiamola per pipe.
SplitStringEsempio5.java
public class SplitStringExample5 { public static void main(String args[]) { //defining a String object String s = 'Life|is|your|creation'; //split string delimited by comma String[] stringarray = s.split('|'); //we can use dot, whitespace, any character //iterate over string array for(int i=0; i<stringarray.length; i++) { prints the tokens system.out.println(stringarray[i]); } < pre> <p> <strong>Output:</strong> </p> <pre> L i f e | i s | y o u r | c r e a t i o n </pre> <p>In the above example, we see that it does not produce the same output as other delimiter yields. It should produce an array of tokens, <strong>life, yours,</strong> and <strong>creation</strong> , but it is not. It gives the result, as we have seen in the output above.</p> <p>The reason behind it that the regular expression engine interprets the pipe delimiter as a <strong>Logical OR operator</strong> . The regex engine splits the String on empty String.</p> <p>In order to resolve this problem, we must <strong>escape</strong> the pipe character when passed to the split() method. We use the following statement to escape the pipe character:</p> <pre> String[] stringarray = s.split('\|'); </pre> <p>Add a pair of <strong>backslash (\)</strong> before the delimiter to escape the pipe. After doing the changes in the above program, the regex engine interprets the pipe character as a delimiter.</p> <p>Another way to escape the pipe character is to put the pipe character inside a pair of square brackets, as shown below. In the Java regex API, the pair of square brackets act as a character class.</p> <pre> String[] stringarray = s.split('[|]'); </pre> <p>Both the above statements yield the following output:</p> <p> <strong>Output:</strong> </p> <pre> Life is your creation </pre> <h3>Using StringTokenizer Class</h3> <p>Java <strong>StringTokenizer</strong> is a legacy class that is defined in java.util package. It allows us to split the string into tokens. It is not used by the programmer because the split() method of the String class does the same work. So, the programmer prefers the split() method instead of the StringTokenizer class. We use the following two methods of the class:</p> <p> <strong>StringTokenizer.hasMoreTokens()</strong> </p> <p>The method iterates over the string and checks if there are more tokens available in the tokenizer string. It returns true if there is one token is available in the string after the current position, else returns false. It internally calls the <strong>nextToken()</strong> method if it returns true and the nextToken() method returns the token.</p> <p> <strong>Syntax:</strong> </p> <pre> public boolean hasMoreTokens() </pre> <p> <strong>StringTokenizer.nextToken()</strong> </p> <p>It returns the next token from the string tokenizer. It throws <strong>NoSuchElementException</strong> if the tokens are not available in the string tokenizer.</p> <p> <strong>Syntax:</strong> </p> <pre> public String nextToken() </pre> <p>Let's create a program that splits the string using the StringTokenizer class.</p> <p> <strong>SplitStringExample6.java</strong> </p> <pre> import java.util.StringTokenizer; public class SplitStringExample6 { public static void main(String[] args) { //defining a String object String str = 'Welcome/to/Javatpoint'; //constructor of the StringTokenizer class StringTokenizer tokens = new StringTokenizer(str, '/'); //checks if the string has more tokens or not while (tokens.hasMoreTokens()) { //prints the tokens System.out.println(tokens.nextToken()); } } } </pre> <p> <strong>Output:</strong> </p> <pre> Welcome to Javatpoint </pre> <h2>Using Scanner.useDelimiter() Method</h2> <p>Java <strong>Scanner</strong> class provides the <strong>useDelimiter()</strong> method to split the string into tokens. There are two variants of the useDelimiter() method:</p> <ul> <li>useDelimiter(Pattern pattern)</li> <li>useDelimiter(String pattern)</li> </ul> <h3>useDelimiter(Pattern pattern)</h3> <p>The method sets the scanner's delimiting pattern to the specified string. It parses a delimiting pattern as an argument. It returns the Scanner.</p> <p> <strong>Syntax:</strong> </p> <pre> public Scanner useDelimiter(Pattern pattern) </pre> <h3>useDelimiter(String pattern)</h3> <p>The method sets the scanner's delimiting pattern to a pattern that constructs from the specified string. It parses a delimiting pattern as an argument. It returns the Scanner.</p> <p> <strong>Syntax:</strong> </p> <pre> public Scanner useDelimiter(String pattern) </pre> <h4>Note: Both the above methods behave in the same way, as invoke the useDelimiter(Pattern.compile(pattern)).</h4> <p>In the following program, we have used the useDelimiter() method to split the string.</p> <p> <strong>SplitStringExample7.java</strong> </p> <pre> import java.util.Scanner; public class SplitStringExample7 { public static void main(String args[]) { //construtor of the Scanner class Scanner scan = new Scanner('Do/your/work/self'); //Initialize the string delimiter scan.useDelimiter('/'); //checks if the tokenized Strings has next token while(scan.hasNext()) { //prints the next token System.out.println(scan.next()); } //closing the scanner scan.close(); } } </pre> <p> <strong>Output:</strong> </p> <pre> Do your work self </pre> <hr></stringarray.length;> Nell'esempio sopra, vediamo che non produce lo stesso output di altri delimitatori. Dovrebbe produrre una serie di token, la vita, la tua, E creazione , ma non è. Fornisce il risultato, come abbiamo visto nell'output sopra.
Il motivo è che il motore delle espressioni regolari interpreta il delimitatore della pipe come a Operatore logico OR . Il motore regex divide la stringa su una stringa vuota.
Per risolvere questo problema dobbiamo fuga il carattere pipe quando viene passato al metodo split(). Usiamo la seguente istruzione per sfuggire al carattere pipe:
1 milione quanti 0
String[] stringarray = s.split('\|');
Aggiungi un paio di barra rovesciata (\) prima del delimitatore per uscire dal tubo. Dopo aver apportato le modifiche nel programma precedente, il motore regex interpreta il carattere pipe come delimitatore.
Un altro modo per sfuggire al carattere pipe è inserire il carattere pipe all'interno di una coppia di parentesi quadre, come mostrato di seguito. Nell'API regex Java, la coppia di parentesi quadre funge da classe di caratteri.
String[] stringarray = s.split('[|]');
Entrambe le affermazioni precedenti producono il seguente output:
Produzione:
Life is your creation
Utilizzo della classe StringTokenizer
Giava StringTokenizer è una classe legacy definita nel pacchetto java.util. Ci permette di dividere la stringa in token. Non viene utilizzato dal programmatore perché il metodo split() della classe String fa lo stesso lavoro. Pertanto, il programmatore preferisce il metodo split() anziché la classe StringTokenizer. Usiamo i seguenti due metodi della classe:
StringTokenizer.hasMoreTokens()
Il metodo esegue un'iterazione sulla stringa e controlla se sono disponibili più token nella stringa del tokenizzatore. Restituisce vero se è disponibile un token nella stringa dopo la posizione corrente, altrimenti restituisce falso. Chiama internamente il prossimoToken() metodo se restituisce true e il metodo nextToken() restituisce il token.
Sintassi:
dattiloscritto ciclo foreach
public boolean hasMoreTokens()
StringTokenizer.nextToken()
Restituisce il token successivo dal tokenizzatore di stringhe. Lancia NoSuchElementException se i token non sono disponibili nel tokenizzatore di stringhe.
Sintassi:
public String nextToken()
Creiamo un programma che divide la stringa utilizzando la classe StringTokenizer.
SplitStringEsempio6.java
import java.util.StringTokenizer; public class SplitStringExample6 { public static void main(String[] args) { //defining a String object String str = 'Welcome/to/Javatpoint'; //constructor of the StringTokenizer class StringTokenizer tokens = new StringTokenizer(str, '/'); //checks if the string has more tokens or not while (tokens.hasMoreTokens()) { //prints the tokens System.out.println(tokens.nextToken()); } } } Produzione:
Welcome to Javatpoint
Utilizzo del metodo Scanner.useDelimiter()
Giava Scanner la classe fornisce il file utilizzareDelimitatore() metodo per dividere la stringa in token. Esistono due varianti del metodo useDelimiter():
- useDelimiter(Modello modello)
- useDelimiter(modello di stringa)
useDelimiter(Modello modello)
Il metodo imposta il modello di delimitazione dello scanner sulla stringa specificata. Analizza un modello di delimitazione come argomento. Restituisce lo scanner.
Sintassi:
public Scanner useDelimiter(Pattern pattern)
useDelimiter(modello di stringa)
Il metodo imposta il modello di delimitazione dello scanner su un modello costruito dalla stringa specificata. Analizza un modello di delimitazione come argomento. Restituisce lo scanner.
Sintassi:
public Scanner useDelimiter(String pattern)
Nota: entrambi i metodi precedenti si comportano allo stesso modo, poiché richiamano useDelimiter(Pattern.compile(pattern)).
Nel seguente programma abbiamo utilizzato il metodo useDelimiter() per dividere la stringa.
SplitStringEsempio7.java
import java.util.Scanner; public class SplitStringExample7 { public static void main(String args[]) { //construtor of the Scanner class Scanner scan = new Scanner('Do/your/work/self'); //Initialize the string delimiter scan.useDelimiter('/'); //checks if the tokenized Strings has next token while(scan.hasNext()) { //prints the next token System.out.println(scan.next()); } //closing the scanner scan.close(); } } Produzione:
Do your work self