Passing directly an array initializer to a method parameter doesn't work

Question

package arraypkg;

import java.util.Arrays;

public class Main
{
    private static void foo(Object o[])
    {
        System.out.printf("%s", Arrays.toString(o));
    }

    public static void main(String[] args)
    {
       Object []o=new Object[]{1,2,3,4,5};
       foo(o);                     //Passing an array of objects to the foo() method.

       foo(new Object[]{6,7,8,9}); //This is valid as obvious.

       Object[] o1 = {1, 2};      //This is also fine.
       foo(o1);

       foo({1,2});               //This looks something similar to the preceding one. This is however wrong and doesn't compile - not a statement.
    }
}

In the preceding code snippet all the expressions except the last one are compiled and run fine. Although the last statement which looks something similar to its immediate statement, the compiler issues a compile-time error - illegal start of expression - not a statement. Why?

Answer 1

foo({1,2});

{1, 2} this kind of array initialization only work at the place you are declaring an array.. At other places, you have to create it using new keyword..

That is why: -

Object[] obj = {1, 2};

Was fine.. This is because, the type of array, is implied by the type of reference we use on LHS.. But, while we use it somewhere else, Compiler cannot find out the type (Like in your case)..

Try using : -

  foo(new Object[]{1,2});