Java break & return

Java break:

public class TestExit {
    public static void main(String[] args) {
        System.out.println("Start Loop.");
        for (int j = 1; j <= 3; j++) {
            System.out.println("This is the outer level of loop(" + j + ").");
            for (int x = 1; x <= 3; x++) {
                System.out.println("This is the inner level of loop(" + x + ").");
                if (true) {
                    break;
                }
            }
        }
        System.out.println("Finish Loop.");
    }
}

prints:

Start Loop.
This is the outer level of loop(1).
This is the inner level of loop(1).
This is the outer level of loop(2).
This is the inner level of loop(1).
This is the outer level of loop(3).
This is the inner level of loop(1).
Finish Loop.

AND

public class TestExit {
    public static void main(String[] args) {
        System.out.println("Start Loop.");
        for (int j = 1; j <= 3; j++) {
            System.out.println("This is the outer level of loop(" + j + ").");
            for (int x = 1; x <= 3; x++) {
                System.out.println("This is the inner level of loop(" + x + ").");
                while (true) {
                    break;
                }
            }
        }
        System.out.println("Finish Loop.");
    }
}

prints:

Start Loop.
This is the outer level of loop(1).
This is the inner level of loop(1).
This is the inner level of loop(2).
This is the inner level of loop(3).
This is the outer level of loop(2).
This is the inner level of loop(1).
This is the inner level of loop(2).
This is the inner level of loop(3).
This is the outer level of loop(3).
This is the inner level of loop(1).
This is the inner level of loop(2).
This is the inner level of loop(3).
Finish Loop.

So we may use

if(some condition) {
  break;
}

but NEVER

while(some condition) {
  break;
}

So when use break to break loop(while loop, for loop, switch loop), it breaks out the nearest loop.

Meanwhile

public class TestExit {
    public static void main(String[] args) {
        System.out.println("Start Loop.");
        for (int j = 1; j <= 3; j++) {
            System.out.println("This is the outer level of loop(" + j + ").");
            for (int x = 1; x <= 3; x++) {
                System.out.println("This is the inner level of loop(" + x + ").");
                if (true) {
                    return;
                }
            }
        }
        System.out.println("Finish Loop.");
    }
}

prints:

Start Loop.
This is the outer level of loop(1).
This is the inner level of loop(1).

And

public class TestExit {
    public static void main(String[] args) {
        System.out.println("Start Loop.");
        for (int j = 1; j <= 3; j++) {
            System.out.println("This is the outer level of loop(" + j + ").");
            for (int x = 1; x <= 3; x++) {
                System.out.println("This is the inner level of loop(" + x + ").");
                while (true) {
                    return;
                }
            }
        }
        System.out.println("Finish Loop.");
    }
}

prints:

Start Loop.
This is the outer level of loop(1).
This is the inner level of loop(1).

And

import android.support.test.runner.AndroidJUnit4;
import android.util.Log;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

@RunWith(AndroidJUnit4.class)
public class TestExit {

    private static final String TAG = TestExit.class.getSimpleName();

    @Before
    public void setUp() throws Exception {
        Log.v(TAG, "This is setup.");
    }

    @After
    public void tearDown() throws Exception {
        Log.v(TAG, "This is teardown.");
    }

    @Test
    public void exitTest() throws Exception {
        Log.v(TAG, "Start the loop.");
        for (int i = 1; i <= 3; i++) {
            Log.v(TAG, "This is the outer loop(" + i + ").");
            for (int j = 1; j <= 3; j++) {
                Log.v(TAG, "This is the inner loop(" + j + ").");
                while (true) {
                    return;
                }
            }
        }
        Log.v(TAG, "Finish the loop.");
    }
}

prints:

1800  1819 V TestExit: This is setup.
1800  1819 V TestExit: Start the loop.
1800  1819 V TestExit: This is the outer loop(1).
1800  1819 V TestExit: This is the inner loop(1).
1800  1819 V TestExit: This is teardown.

So return breaks the entire method.

In general, break breaks loop, return breaks method.