Return different type of data from a method in java?

Question

public static void main(String args[]) {     myMethod(); // i am calling static method from main()  } 

.

public static ? myMethod(){ // ? = what should be the return type     return value;// is String     return index;// is int } 

myMethod() will return String and int value. So take these returning values from main() i came up with following solution.

create a class call ReturningValues

public class ReturningValues { private String value; private int index;  // getters and setters here } 

and change myMethod() as follows.

 public static ReturningValues myMethod() {     ReturningValues rv = new ReturningValues();     rv.setValue("value");     rv.setIndex(12);     return rv; } 

Now my question,is there any easier way to achieve this??

Answer 1

I create various return types using enum. It doesn't defined automatically. That implementation look like factory pattern.

public  enum  SmartReturn {      IntegerType, DoubleType;      @SuppressWarnings("unchecked")     public <T> T comeback(String value) {         switch (this) {             case IntegerType:                 return (T) Integer.valueOf(value);             case DoubleType:                 return (T) Double.valueOf(value);             default:                 return null;         }     } } 

Unit Test:

public class MultipleReturnTypeTest {    @Test   public void returnIntegerOrString() {      Assert.assertTrue(SmartReturn.IntegerType.comeback("1") instanceof Integer);      Assert.assertTrue(SmartReturn.DoubleType.comeback("1") instanceof Double);   }  } 

Answer 2

No. Java methods can only return one result (void, a primitive, or an object), and creating a struct-type class like this is exactly how you do it.

As a note, it is frequently possible to make classes like your ReturningValues immutable like this:

public class ReturningValues {     public final String value;     public final int index;      public ReturningValues(String value, int index) {         this.value = value;         this.index = index;     } } 

This has the advantage that a ReturningValues can be passed around, such as between threads, with no concerns about accidentally getting things out of sync.