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Return statement

The return statement is a very simple one. It just finishes the running of code in the current method and "returns" to the method’s caller.

A method in Java can return a value if the method needs to.

Let’s look at how return statements work with a practical example. Say we have a couple of methods in our program:

int minorHit = 3;
int majorHit = 7;

public boolean adjustHealth(Player player, int hit) {
    player.health = player.health - hit;

    return isAlive(player);
}

public boolean isAlive(Player player) {
    if (player.health >= 20) {
        return true;
    } else { // player has died!
        return false;
    }
}

If someplace in our code we were to do something like:

// big hit!
boolean isPlayerAlive = adjustHealth(playerOne, majorHit);

if (isPlayerAlive == false) endGame();

You can see how when we call the method "adjustHealth()" it returns the result of calling isAlive(player), and we make a decision to end the game if the player has died.

Notice that you can have multiple return statements in methods. Each return statement can return a different value depending on the conditions.

If a method is marked void then it does not return a value. However, void methods can still use return statements to stop execution early.

public void printStatus(String message) {
    System.err.println(message);
    return;
}

In this void method, the return statement doesn’t return a value. It simply signals that the method has finished executing.

Chapter Exercises

Try these exercises in jshell to practice working with return statements and methods:

Exercise 1: Simple Return Method

Create a method that takes two integers and returns their sum:

int addNumbers(int a, int b) {
    return a + b;
}

Test it: addNumbers(5, 3) should return 8

Exercise 2: Boolean Return Method

Create a method that checks if a number is positive:

boolean isPositive(int number) {
    return number > 0;
}

Test it: isPositive(5) should return true, isPositive(-3) should return false

Exercise 3: String Return Method

Create a method that returns a greeting message:

String createGreeting(String name) {
    return "Hello, " + name + "!";
}

Test it: createGreeting("Alice") should return "Hello, Alice!"

Exercise 4: Multiple Return Paths

Create a method that returns different messages based on a grade:

String getGradeMessage(int grade) {
    if (grade >= 90) {
        return "Excellent!";
    } else if (grade >= 70) {
        return "Good job!";
    } else {
        return "Keep trying!";
    }
}

Test it with different values: getGradeMessage(95), getGradeMessage(75), getGradeMessage(65)
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