Java if Else with Examples and programs

Java Conditions and If Statements

Java supports the usual logical conditions from mathematics:

• Less than: a < b
• Less than or equal to: a <= b
• Greater than: a > b
• Greater than or equal to a >= b
• Equal to a == b
• Not Equal to: a != b

You can use these conditions to perform different actions for different decisions.

Java has the following conditional statements:

• Use if to specify a block of code to be executed, if a specified condition is true
• Use else to specify a block of code to be executed, if the same condition is false
• Use else if to specify a new condition to test, if the first condition is false
• Use switch to specify many alternative blocks of code to be executed

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The if Statement

Use the statementif to specify a block of Java code to be executed if a condition is.true

Syntax

if (condition) {
  // block of code to be executed if the condition is true}

Note that isif in lowercase letters. Uppercase letters (If or IF) will generate an error.

In the example below, we test two values to find out if 20 is greater than 18. If the condition is,true print some text:

Example

if (20 > 18) {
  System.out.println("20 is greater than 18");
}

Run example »

We can also test variables:

Example

int x = 20;
int y = 18;
if (x > y) {
  System.out.println("x is greater than y");
}

Run example »

Example explained

In the example above we use two variables, x, and y, to test whether x is greater than y (using the operator>). As x is 20, and y is 18, and we know that 20 is greater than 18, we print to the screen that "x is greater than y".

The else Statement

Use the statementelse to specify a block of code to be executed if the condition is.false

Syntax

if (condition) {
  // block of code to be executed if the condition is true} else { 
  // block of code to be executed if the condition is false
} 

Example

int time = 20;
if (time < 18) {
  System.out.println("Good day.");
} else {
  System.out.println("Good evening.");
}
// Outputs "Good evening."

Run example »

Example explained

In the example above, time (20) is greater than 18, so the condition is false, so we move on to the else condition and print to the screen "Good evening". If the time was less than 18, the program would print "Good day".

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The else if Statement

Use the statementelse if to specify a new condition if the first condition is.false

Syntax

if (condition1) {
  // block of code to be executed if condition1 is true} else if (condition2) {
  // block of code to be executed if the condition1 is false and condition2 is true
} else {
  // block of code to be executed if the condition1 is false and condition2 is false
}

Example

int time = 22;
if (time < 10) {
  System.out.println("Good morning.");
} else if (time < 20) {
  System.out.println("Good day.");
} else {
  System.out.println("Good evening.");
}
// Outputs "Good evening."

Run example »

Example explained

In the example above, time (22) is greater than 10, so the first condition is.false The next condition, in the statementelse if, is also,false so we move on to the conditionelse since condition1 and condition2 is both false- and print to the screen "Good evening".

However, if the time was 14, our program would print "Good day."

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Short Hand If...Else (Ternary Operator)

If you have only one statement to execute, one for,if and one for,else you can put it all on the same line:

Syntax

variable = (condition) ? expressionTrue : expressionFalse;

Instead of writing:

Example

int time = 20;
if (time < 18) {
  System.out.println("Good day.");
} else {
  System.out.println("Good evening.");
}

Run example »

You can simply write:

Example

int time = 20;
String result = (time < 18) ? "Good day." : "Good evening.";
System.out.println(result);

Run example »

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Test Yourself With Exercises

Exercise:

Print "Hello World" if x is greater than y.

int x = 50;
int y = 10;
 (x  y) {
  System.out.println("Hello World");
}