How to return 2 values from a Java method

Question

I am trying to return 2 values from a Java method but I get these errors  Here is my code      Method code public static int something        int number1   1      int number2   2       return number1  number2        Main method 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

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I m curious as to why nobody has come up with the more elegant callback solution   So instead of using a return type you use a handler passed into the method as an argument   The example below has the two contrasting approaches   I know which of the two is more elegant to me   -   public class DiceExample        public interface Pair lt T1  T2 gt            T1 getLeft             T2 getRight               private Pair lt Integer  Integer gt  rollDiceWithReturnType              double dice1    Math random     6           double dice2    Math random     6            return new Pair lt Integer  Integer gt                   Override             public Integer getLeft                     return  int  Math ceil dice1                               Override             public Integer getRight                     return  int  Math ceil dice2                                        FunctionalInterface     public interface ResultHandler           void handleDice int ceil  int ceil2              private void rollDiceWithResultHandler ResultHandler resultHandler            double dice1    Math random     6           double dice2    Math random     6            resultHandler handleDice  int  Math ceil dice1    int  Math ceil dice2               public static void main String   args             DiceExample object   new DiceExample              Pair lt Integer  Integer gt  result   object rollDiceWithReturnType            System out println  Dice 1      result getLeft             System out println  Dice 2      result getRight              object rollDiceWithResultHandler  dice1  dice2  - gt                System out println  Dice 1      dice1               System out println  Dice 2      dice2

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You can only return one value in Java  so the neatest way is like this   return new Pair lt Integer gt  number1  number2     Here s an updated version of your code   public class Scratch          Function code     public static Pair lt Integer gt  something             int number1   1          int number2   2          return new Pair lt Integer gt  number1  number2                 Main class code     public static void main String   args            Pair lt Integer gt  pair   something            System out println pair first     pair second              class Pair lt T gt        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

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You also can send in mutable objects as parameters  if you use methods to modify them then they will be modified when you return from the function  It won t work on stuff like Float  since it is immutable   public class HelloWorld        public static void main String   args           HelloWorld world   new HelloWorld             world run                  private class Dog              private String name         public void setName String s                      name   s                  public String getName     return name          public Dog String name                      setName name                       public void run                Dog newDog   new Dog  John           nameThatDog newDog          System out println newDog getName                   public void nameThatDog Dog dog                  dog setName  Rutger               The result is  Rutger

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Here is the really simple and short solution with SimpleEntry   AbstractMap Entry lt String  Float gt  myTwoCents new AbstractMap SimpleEntry lt  gt   maximum possible performance reached    99 9f    String question myTwoCents getKey    Float answer myTwoCents getValue      Only uses Java built in functions and it comes with the type safty benefit

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In my opinion the best is to create a new class which constructor is the function you need  e g    public class pairReturn            name your parameters          public int sth1          public double sth2          public pairReturn int param                 place the code of your function  e g               sth1 param 5              sth2 param 10                    Then simply use the constructor as you would use the function   pairReturn pR   new pairReturn 15     and you can use pR sth1  pR sth2 as  2 results of the function

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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

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Use a Pair Tuple type object   you don t even need to create one if u depend on Apache commons-lang  Just use the Pair class

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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

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Return an Array Of Objects  private static Object   f             double x  1 0         int y  2        return new Object   Double valueOf x  Integer valueOf y

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You don t need to create your own class to return two different values  Just use a HashMap like this   private HashMap lt Toy  GameLevel gt  getToyAndLevelOfSpatial Spatial spatial        Toy toyWithSpatial   firstValue      GameLevel levelToyFound   secondValue       HashMap lt Toy GameLevel gt  hm new HashMap lt  gt         hm put toyWithSpatial  levelToyFound       return hm     private void findStuff         HashMap lt Toy  GameLevel gt  hm   getToyAndLevelOfSpatial spatial       Toy firstValue   hm keySet   iterator   next        GameLevel secondValue   hm get firstValue       You even have the benefit of type safety

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First  it would be better if Java had tuples for returning multiple values   Second  code the simplest possible Pair class  or use an array   But  if you do need to return a pair  consider what concept it represents  starting with its field names  then class name  - and whether it plays a larger role than you thought  and if it would help your overall design to have an explicit abstraction for it  Maybe it s a code hint    Please Note  I m not dogmatically saying it will help  but just to look  to see if it does    or if it does not

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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 lt Integer gt  list   new ArrayList lt Integer gt             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 lt Integer gt  numList   something

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public class Mulretun       public String name       public String location      public String   getExample                 String ar     new String 2           ar 0   siva           ar 1   dallas           return ar    returning two values at once           public static void main String   args                Mulretun m new Mulretun            String ar    m getExample            int i          for i 0 i lt ar length i            System out println  return values are      ar i                    o p  return values are  siva return values are  dallas

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You could implement a generic Pair if you are sure that you just need to return two values   public class Pair lt U  V gt                 The first element of this  lt code gt Pair lt  code gt              private U first                  The second element of this  lt code gt Pair lt  code gt              private V second                  Constructs a new  lt code gt Pair lt  code gt  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 lt Object  Object gt  getSomePair

[java] How to return 2 values from a Java method?

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