Multiple return values

A method is called. It returns 3 values—2 ints and a String. In Java we must use a class instance, an array or other collection to return these values.

With an object array, we can return many different types of elements. But the simplest and best solution involves a class. We can return a class with multiple values.

Object array example

Here we introduce a getSizes method that returns an Object array. It can return any number of elements, and these can have any type.

import java.util.Arrays;

public class Program {

    public static Object[] getSizes() {
        // Return 3 values from this method.
        // ... Return ints and strings.
        Object[] array = new Object[3];
        array[0] = 10;
        array[1] = "cat";
        array[2] = 30;
        return array;
    }

    public static void main(String[] args) {
        // Call method with multiple return values.
        Object[] sizes = getSizes();
        System.out.println(Arrays.toString(sizes));
    }
}
[10, cat, 30]

Return class instance

Here we create a class instance inside a method and return that. The computeDog() method returns a Dog object.

class Dog {
    public int weight;
    public String name;
}

public class Program {

    public static Dog computeDog() {
        // Return multiple values in an object instance.
        Dog dog = new Dog();
        dog.weight = 40;
        dog.name = "Spark";
        return dog;
    }

    public static void main(String[] args) {
        Dog dog = computeDog();

        // Print return values.
        int weight = dog.weight;
        String name = dog.name;
        System.out.println(weight);
        System.out.println(name);
    }
}
40
Spark

For many return values, or a variable number of return values, an ArrayList is effective. Return an ArrayList from your method. A type like Integer (or Object) can be used.

In Java objects are meant to encapsulate data. So multiple return values are often placed in objects. With methods and logic, we have object-orientation.