Understanding the Java `break` Keyword with Examples

Introduce Java break Keyword and give examples

The break keyword in Java is used to terminate a loop or a switch statement prematurely. When the break statement is encountered, the control flow of the program jumps to the statement immediately following the loop or switch block. This can be particularly useful when you want to exit a loop based on a certain condition.

Using break in Loops

The break statement can be used in various types of loops, such as for, while, and do-while loops.

Example 1: Using break in a for loop

public class BreakExample {
    public static void main(String[] args) {
        for (int i = 1; i <= 10; i++) {
            if (i == 5) {
                break; // Exit the loop when i is 5
            }
            System.out.println(i);
        }
        System.out.println("Loop terminated.");
    }
}

Output:

1
2
3
4
Loop terminated.

In this example, the loop prints numbers from 1 to 4. When i reaches 5, the break statement is executed, and the loop is terminated.

Example 2: Using break in a while loop

public class BreakWhileExample {
    public static void main(String[] args) {
        int i = 1;
        while (i <= 10) {
            if (i == 7) {
                break; // Exit the loop when i is 7
            }
            System.out.println(i);
            i++;
        }
        System.out.println("Loop terminated.");
    }
}

Output:

1
2
3
4
5
6
Loop terminated.

In this example, the while loop prints numbers from 1 to 6. When i reaches 7, the break statement is executed, and the loop is terminated.

Using break in Switch Statements

The break statement is also commonly used in switch statements to prevent fall-through behavior, where execution continues into the next case.

Example 3: Using break in a switch statement

public class BreakSwitchExample {
    public static void main(String[] args) {
        int day = 3;
        String dayName;

        switch (day) {
            case 1:
                dayName = "Monday";
                break; // Exit the switch after this case
            case 2:
                dayName = "Tuesday";
                break; // Exit the switch after this case
            case 3:
                dayName = "Wednesday";
                break; // Exit the switch after this case
            case 4:
                dayName = "Thursday";
                break; // Exit the switch after this case
            case 5:
                dayName = "Friday";
                break; // Exit the switch after this case
            case 6:
                dayName = "Saturday";
                break; // Exit the switch after this case
            case 7:
                dayName = "Sunday";
                break; // Exit the switch after this case
            default:
                dayName = "Invalid day";
                break; // Exit the switch after this case
        }

        System.out.println("Day: " + dayName);
    }
}

Output:

Day: Wednesday

In this example, the switch statement checks the value of day. When it matches case 3, it assigns "Wednesday" to dayName and then executes the break statement to exit the switch.

Summary

• The break keyword is used to exit loops and switch statements prematurely.
• In loops, it can be used to stop iteration based on a condition.
• In switch statements, it prevents fall-through behavior, ensuring that only the matched case is executed.