IL Giava se dichiarazione viene utilizzato per testare la condizione. Controlla booleano condizione: VERO O falso . Esistono vari tipi di istruzioni if in Java.
- se dichiarazione
- istruzione if-else
- scala se-altro-se
- istruzione if nidificata
Java se istruzione
L'istruzione if Java verifica la condizione. Esegue il se blocco se la condizione è vera.
Sintassi:
if(condition){ //code to be executed } 
Esempio:
//Java Program to demonstate the use of if statement. public class IfExample { public static void main(String[] args) { //defining an 'age' variable int age=20; //checking the age if(age>18){ System.out.print('Age is greater than 18'); } } } Provalo adesso Produzione:
come rivelare le app nascoste
Age is greater than 18
Istruzione Java if-else
Anche l'istruzione Java if-else verifica la condizione. Esegue il se blocco se la condizione è vera altrimenti altrimenti blocca viene eseguito.
Sintassi:
if(condition){ //code if condition is true }else{ //code if condition is false } 
Esempio:
//A Java Program to demonstrate the use of if-else statement. //It is a program of odd and even number. public class IfElseExample { public static void main(String[] args) { //defining a variable int number=13; //Check if the number is divisible by 2 or not if(number%2==0){ System.out.println('even number'); }else{ System.out.println('odd number'); } } } Provalo adesso Produzione:
b+ albero
odd number
Esempio di anno bisestile:
Un anno è bisestile se è divisibile per 4 e 400. Ma non per 100.
public class LeapYearExample { public static void main(String[] args) { int year=2020; if(((year % 4 ==0) && (year % 100 !=0)) || (year % 400==0)){ System.out.println('LEAP YEAR'); } else{ System.out.println('COMMON YEAR'); } } } Produzione:
LEAP YEAR
Utilizzo dell'operatore ternario
Possiamo anche utilizzare l'operatore ternario (? :) per eseguire il compito dell'istruzione if...else. È un modo abbreviato per verificare la condizione. Se la condizione è vera, il risultato di ? viene restituito. Ma, se la condizione è falsa, viene restituito il risultato di :.
Esempio:
public class IfElseTernaryExample { public static void main(String[] args) { int number=13; //Using ternary operator String output=(number%2==0)?'even number':'odd number'; System.out.println(output); } } Produzione:
carattere da stringa in Java
odd number
Istruzione Java if-else-if ladder
L'istruzione ladder if-else-if esegue una condizione da più istruzioni.
Sintassi:
if(condition1){ //code to be executed if condition1 is true }else if(condition2){ //code to be executed if condition2 is true } else if(condition3){ //code to be executed if condition3 is true } ... else{ //code to be executed if all the conditions are false } 
Esempio:
css per il grassetto
//Java Program to demonstrate the use of If else-if ladder. //It is a program of grading system for fail, D grade, C grade, B grade, A grade and A+. public class IfElseIfExample { public static void main(String[] args) { int marks=65; if(marks=50 && marks=60 && marks=70 && marks=80 && marks=90 && marks<100){ system.out.println('a+ grade'); }else{ system.out.println('invalid!'); } < pre> <p>Output:</p> <pre>C grade </pre> <p> <strong>Program to check POSITIVE, NEGATIVE or ZERO:</strong> </p> <pre> public class PositiveNegativeExample { public static void main(String[] args) { int number=-13; if(number>0){ System.out.println('POSITIVE'); }else if(number<0){ system.out.println('negative'); }else{ system.out.println('zero'); } < pre> <p>Output:</p> <pre>NEGATIVE </pre> <h2>Java Nested if statement</h2> <p>The nested if statement represents the <em>if block within another if block</em> . Here, the inner if block condition executes only when outer if block condition is true. </p> <p> <strong>Syntax:</strong> </p> <pre> if(condition){ //code to be executed if(condition){ //code to be executed } } </pre> <p> <strong>Example:</strong> </p> <pre> //Java Program to demonstrate the use of Nested If Statement. public class JavaNestedIfExample { public static void main(String[] args) { //Creating two variables for age and weight int age=20; int weight=80; //applying condition on age and weight if(age>=18){ if(weight>50){ System.out.println('You are eligible to donate blood'); } } }} </pre> <span> Test it Now </span> <p>Output:</p> <pre>You are eligible to donate blood </pre> <p> <strong>Example 2:</strong> </p> <pre> //Java Program to demonstrate the use of Nested If Statement. public class JavaNestedIfExample2 { public static void main(String[] args) { //Creating two variables for age and weight int age=25; int weight=48; //applying condition on age and weight if(age>=18){ if(weight>50){ System.out.println('You are eligible to donate blood'); } else{ System.out.println('You are not eligible to donate blood'); } } else{ System.out.println('Age must be greater than 18'); } } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> You are not eligible to donate blood </pre> <hr></0){></pre></100){> Programma per verificare POSITIVO, NEGATIVO o ZERO:
public class PositiveNegativeExample { public static void main(String[] args) { int number=-13; if(number>0){ System.out.println('POSITIVE'); }else if(number<0){ system.out.println(\'negative\'); }else{ system.out.println(\'zero\'); } < pre> <p>Output:</p> <pre>NEGATIVE </pre> <h2>Java Nested if statement</h2> <p>The nested if statement represents the <em>if block within another if block</em> . Here, the inner if block condition executes only when outer if block condition is true. </p> <p> <strong>Syntax:</strong> </p> <pre> if(condition){ //code to be executed if(condition){ //code to be executed } } </pre> <p> <strong>Example:</strong> </p> <pre> //Java Program to demonstrate the use of Nested If Statement. public class JavaNestedIfExample { public static void main(String[] args) { //Creating two variables for age and weight int age=20; int weight=80; //applying condition on age and weight if(age>=18){ if(weight>50){ System.out.println('You are eligible to donate blood'); } } }} </pre> <span> Test it Now </span> <p>Output:</p> <pre>You are eligible to donate blood </pre> <p> <strong>Example 2:</strong> </p> <pre> //Java Program to demonstrate the use of Nested If Statement. public class JavaNestedIfExample2 { public static void main(String[] args) { //Creating two variables for age and weight int age=25; int weight=48; //applying condition on age and weight if(age>=18){ if(weight>50){ System.out.println('You are eligible to donate blood'); } else{ System.out.println('You are not eligible to donate blood'); } } else{ System.out.println('Age must be greater than 18'); } } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> You are not eligible to donate blood </pre> <hr></0){> Java Istruzione if nidificata
L'istruzione if nidificata rappresenta il se blocco all'interno di un altro se blocco . In questo caso, la condizione interna se del blocco viene eseguita solo quando la condizione esterna se del blocco è vera.
Sintassi:
if(condition){ //code to be executed if(condition){ //code to be executed } } Esempio:
//Java Program to demonstrate the use of Nested If Statement. public class JavaNestedIfExample { public static void main(String[] args) { //Creating two variables for age and weight int age=20; int weight=80; //applying condition on age and weight if(age>=18){ if(weight>50){ System.out.println('You are eligible to donate blood'); } } }} Provalo adesso Produzione:
You are eligible to donate blood
Esempio 2:
//Java Program to demonstrate the use of Nested If Statement. public class JavaNestedIfExample2 { public static void main(String[] args) { //Creating two variables for age and weight int age=25; int weight=48; //applying condition on age and weight if(age>=18){ if(weight>50){ System.out.println('You are eligible to donate blood'); } else{ System.out.println('You are not eligible to donate blood'); } } else{ System.out.println('Age must be greater than 18'); } } } Provalo adesso Produzione:
testo di avvolgimento css
You are not eligible to donate blood