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Lesson 26. Using break, continue, and return in Java | Learn Java Basics

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Belongs to Category: Learn Basic Java|Posted by: Le Thanh Giang||5 min read
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Lesson 26. How to Use break, continue, and return in Java | Learn Java Basics

In Java programming, the break, continue, and return statements are used to control the program's execution flow, especially within loops and methods.

  • break is used to immediately exit a loop or a switch-case.
  • continue skips the current iteration and moves to the next loop iteration.
  • return immediately exits a method and can return a value.

This article provides a detailed guide on how to use these statements with practical examples.

The break Statement in Java

Using break in Loops

The break statement stops a for, while, or do-while loop immediately when a specified condition is met.

Example: Stop the loop when i == 5:

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 = 5
            }
            System.out.println(i);
        }
        System.out.println("Loop has ended.");
    }
}

Output:

1
2
3
4
Loop has ended.

When i == 5, the break statement is executed, terminating the for loop immediately.

Using break in switch-case

In switch-case, break prevents the program from executing subsequent cases after a match is found.

Example:

public class BreakSwitchExample {
    public static void main(String[] args) {
        int number = 2;

        switch (number) {
            case 1:
                System.out.println("One");
                break;
            case 2:
                System.out.println("Two");
                break;
            case 3:
                System.out.println("Three");
                break;
            default:
                System.out.println("Not recognized");
        }
    }
}

Output:

Two

Without break, the program would continue executing the next cases.

Using break with Labels

The break statement can be used with a label to exit nested loops.

Example: Exit the entire loop when i == 2 and j == 2:

public class BreakWithLabel {
    public static void main(String[] args) {
        outerLoop:
        for (int i = 0; i < 5; i++) {
            for (int j = 0; j < 5; j++) {
                if (i == 2 && j == 2) {
                    break outerLoop;  // Exit the outer loop
                }
                System.out.println("i = " + i + ", j = " + j);
            }
        }
        System.out.println("Loop has ended.");
    }
}

The continue Statement in Java

Using continue in Loops

The continue statement skips the current iteration and moves to the next iteration of the loop.

Example: Skip when i == 5:

public class ContinueExample {
    public static void main(String[] args) {
        for (int i = 1; i <= 10; i++) {
            if (i == 5) {
                continue;  // Skip this iteration
            }
            System.out.println(i);
        }
    }
}

Output:

1
2
3
4
6
7
8
9
10

When i == 5, the program skips System.out.println(i); and moves to i = 6.

Using continue with Labels

The continue statement with a label skips the remaining loop body and jumps to the next iteration of the outer loop.

Example: When i == 2 and j == 2, skip the rest of i:

public class ContinueWithLabel {
    public static void main(String[] args) {
        outerLoop:
        for (int i = 0; i < 5; i++) {
            for (int j = 0; j < 5; j++) {
                if (i == 2 && j == 2) {
                    continue outerLoop; // Skip the rest of the current iteration of i
                }
                System.out.println("i = " + i + ", j = " + j);
            }
        }
        System.out.println("Loop has ended.");
    }
}

The return Statement in Java

Using return in Methods

The return statement is used to exit a method and optionally return a value.

Example: Calculate the sum of two numbers:

public class ReturnExample {
    public static void main(String[] args) {
        System.out.println("Sum of 3 and 4: " + calculateSum(3, 4));
    }

    public static int calculateSum(int a, int b) {
        return a + b;  // Return the sum
    }
}

Output:

Sum of 3 and 4: 7

Using return to Exit a Method Early

public class ReturnEarlyExample {
    public static void main(String[] args) {
        System.out.println(checkPositiveNumber(-5));
    }

    public static String checkPositiveNumber(int num) {
        if (num <= 0) {
            return "Invalid number";  // Exit immediately
        }
        return "Valid positive number";
    }
}

Using return in Loops

When return is used inside a loop, the method exits immediately.

public class ReturnInLoop {
    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5};
        System.out.println("Found number: " + findNumber(arr, 3));
    }

    public static int findNumber(int[] arr, int target) {
        for (int num : arr) {
            if (num == target) {
                return num;  // Return immediately when found
            }
        }
        return -1;  // Not found
    }
}

In Java, return inside a loop will terminate the method that the loop is executing, rather than just exiting the loop like break or continue. When return is called inside a loop, the program will exit the loop and immediately exit the method, returning a value (if applicable) to the caller of that method.

Conclusion

  • break: Exits a loop when a condition is met.
  • continue: Skips the current iteration and moves to the next loop iteration.
  • return: Immediately exits a method.

Understanding these control flow statements helps improve your Java programming skills and optimize your code execution.

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