how to return 2 values from a java function?

Question

Here is my code:

// Function code
public static int something(){
    int number1 = 1;
    int number2 = 2;
    return number1, number2;
}

// Main class code
public static void main(String[] args) {
  something();
  System.out.println(number1 + number2);
}

Error:

Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - missing return statement
    at assignment.Main.something(Main.java:86)
    at assignment.Main.main(Main.java:53)

Java Result: 1

Answer 1

you have to use collections to return more then one return values

in your case you write your code as

public static List something(){
        List<Integer> list = new ArrayList<Integer>();
        int number1 = 1;
        int number2 = 2;
        list.add(number1);
        list.add(number2);
        return list;
    }

    // Main class code
    public static void main(String[] args) {
      something();
      List<Integer> numList = something();
    }

Answer 2

Java does not support multi-value returns. Return an array of values.

// Function code
public static int[] something(){
    int number1 = 1;
    int number2 = 2;
    return new int[] {number1, number2};
}

// Main class code
public static void main(String[] args) {
  int result[] = something();
  System.out.println(result[0] + result[1]);
}

Answer 3

You can only return one value in Java, so the neatest way is like this:

return new Pair<Integer>(number1, number2);

Here's an updated version of your code:

public class Scratch
{
    // Function code
    public static Pair<Integer> something() {
        int number1 = 1;
        int number2 = 2;
        return new Pair<Integer>(number1, number2);
    }

    // Main class code
    public static void main(String[] args) {
        Pair<Integer> pair = something();
        System.out.println(pair.first() + pair.second());
    }
}

class Pair<T> {
    private final T m_first;
    private final T m_second;

    public Pair(T first, T second) {
        m_first = first;
        m_second = second;
    }

    public T first() {
        return m_first;
    }

    public T second() {
        return m_second;
    }
}

Answer 4

Try this :

// Function code
public static int[] something(){
    int number1 = 1;
    int number2 = 2;
    return new int[] {number1, number2};
}

// Main class code
public static void main(String[] args) {
  int[] ret = something();
  System.out.println(ret[0] + ret[1]);
}

Answer 5

You could implement a generic Pair if you are sure that you just need to return two values:

public class Pair<U, V> {

 /**
     * The first element of this <code>Pair</code>
     */
    private U first;

    /**
     * The second element of this <code>Pair</code>
     */
    private V second;

    /**
     * Constructs a new <code>Pair</code> with the given values.
     * 
     * @param first  the first element
     * @param second the second element
     */
    public Pair(U first, V second) {

        this.first = first;
        this.second = second;
    }

//getter for first and second

and then have the method return that Pair:

public Pair<Object, Object> getSomePair();

Answer 6

Instead of returning an array that contains the two values or using a generic Pair class, consider creating a class that represents the result that you want to return, and return an instance of that class. Give the class a meaningful name. The benefits of this approach over using an array are type safety and it will make your program much easier to understand.

Note: A generic Pair class, as proposed in some of the other answers here, also gives you type safety, but doesn't convey what the result represents.

Example (which doesn't use really meaningful names):

final class MyResult {
    private final int first;
    private final int second;

    public MyResult(int first, int second) {
        this.first = first;
        this.second = second;
    }

    public int getFirst() {
        return first;
    }

    public int getSecond() {
        return second;
    }
}

// ...

public static MyResult something() {
    int number1 = 1;
    int number2 = 2;

    return new MyResult(number1, number2);
}

public static void main(String[] args) {
    MyResult result = something();
    System.out.println(result.getFirst() + result.getSecond());
}