Java If ... Else

Java If ... Else Statements

Java supports the usual logical conditions from mathematics. You can use these conditions to perform different actions for different decisions. This is called conditional logic.

• a < b (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)

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.

1. The if Statement

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

public class Main {
  public static void main(String[] args) {
    int time = 20;
    if (time < 18) {
      System.out.println("Good day.");
    }
    // Since the condition is false, nothing is printed.
  }
}

2. The else Statement

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

public class Main {
  public static void main(String[] args) {
    int time = 20;
    if (time < 18) {
      System.out.println("Good day.");
    } else {
      System.out.println("Good evening.");
    }
    // Outputs "Good evening."
  }
}

3. The else if Statement

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

public class Main {
  public static void main(String[] args) {
    int time = 22;
    if (time < 10) {
      System.out.println("Good morning.");
    } else if (time < 18) {
      System.out.println("Good day.");
    } else {
      System.out.println("Good evening.");
    }
    // Outputs "Good evening."
  }
}

4. Ternary Operator

There is also a short-hand if-else, which is known as the ternary operator because it consists of three operands. It can be used to replace simple if-else blocks.

Syntax: variable = (condition) ? expressionTrue : expressionFalse;

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