Return inside loops in Java - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Java code with return inside a loop?

Consider the following Java method. What will be printed when testReturn() is called?

Java

public class Test {
    public static int testReturn() {
        for (int i = 0; i < 5; i++) {
            if (i == 2) {
                return i;
            }
        }
        return -1;
    }

    public static void main(String[] args) {
        System.out.println(testReturn());
    }
}

A 2

B 5

C Compilation error

D -1

💡 Hint

Remember that return exits the method immediately.

The loop runs from 0 to 4. When i is 2, the method returns 2 immediately, so the output is 2.

❓ Predict Output

intermediate

What does this method return?

What value does the method findFirstEven return when called?

Java

public class Test {
    public static int findFirstEven(int[] numbers) {
        for (int num : numbers) {
            if (num % 2 == 0) {
                return num;
            }
        }
        return -1;
    }

    public static void main(String[] args) {
        System.out.println(findFirstEven(new int[]{1, 3, 5, 6, 8}));
    }
}

A 5

B 1

C -1

D 6

💡 Hint

The method returns the first even number it finds.

The first even number in the array is 6, so the method returns 6.

🔧 Debug

advanced

What error occurs in this code with return inside a loop?

What error does this Java code produce when compiled?

Java

public class Test {
    public static int test() {
        for (int i = 0; i < 3; i++) {
            if (i == 1) {
                return i;
            }
        }
        // Missing return statement here
        return -1;
    }
}

A Compilation error: missing return statement

B Runtime exception: NullPointerException

C Returns 1

D Compilation error: unreachable code

💡 Hint

Check if all code paths return a value.

The method must return an int on all paths. If the loop never returns, there is no return statement after the loop, causing a compilation error.

❓ Predict Output

advanced

What is printed by this method with return inside nested loops?

What does the following Java method print when called?

Java

public class Test {
    public static int nestedReturn() {
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                if (i * j > 2) {
                    return i + j;
                }
            }
        }
        return -1;
    }

    public static void main(String[] args) {
        System.out.println(nestedReturn());
    }
}

A -1

B 3

C 4

D 5

💡 Hint

Look for the first time i * j > 2 is true.

The first time i * j > 2 is true is when i=2 and j=2 (2*2=4 > 2). Then return 2+2=4. The output is 4.

❓ Predict Output

expert

What is the output of this method with return inside a loop and try-catch?

What does this Java method print when called?

Java

public class Test {
    public static int trickyReturn() {
        for (int i = 0; i < 3; i++) {
            try {
                if (i == 1) {
                    return i;
                }
            } catch (Exception e) {
                return -1;
            }
        }
        return -2;
    }

    public static void main(String[] args) {
        System.out.println(trickyReturn());
    }
}

A -1

B 1

C -2

D Compilation error

💡 Hint

Consider if any exception is thrown inside the try block.

No exception is thrown, so when i == 1, the method returns 1 immediately.