如何将 object 转换为 java 中的双精度型数组？

Question

OK so what if i have a method like:

Object[] myTest(int[] a, double[] b){
   return new Object[]{a,b};
}

Now How can i cast the result Object to int[] and double[]?

Like if i use:

int[] array1 = (int[]) myTest(a,b)[0];
double[] array2 = (double[]) myTest(a,b)[1];

But this does not work. Or is there any efficient method to do this job?

Answer 1

Have a WrapperObject that contains int[] and double[]. Use getters to access them.

public class WrapperObject {

     private int[] a;
     private double[] b;

     public void setA(int[] a1) {
         a = a1;
     }

     public int[] getA() {
         return a;
     }
    .....
}

Let your myTest method return that object.

public WrapperObject myTest(int[] a , double[] b) {
      return new WrapperObject(a, b);
}

Answer 2

Although your code is working fine with me, but you could do it in another way:

public static Object myTest(int[] a, double[] b, int index)
{
    Object[] obj = {a,b};
    return obj[index];
}

Then use it like:

int[] array1 = (int[]) myTest(a,b,0);
double[] array2 = (double[]) myTest(a,b,1);

Answer 3

You could use a wrapper:

Integer[] array = (Integer[]) myTest()

Answer 4

Not sure why you're having difficulty: on Java 6 this works as expected.

Try compiling this class and running it:

public class t1
{
    public static void main(String[] args) throws Exception
    {
    int[] a = new int[1];
    double[] b = new double[1];

    int[] array1 = (int[]) myTest(a,b)[0];
    double[] array2 = (double[]) myTest(a,b)[1];
    System.err.println(array1);
    System.err.println(array2);
    }

    static Object[] myTest(int[] a, double[] b){
    return new Object[]{a,b};
    }
}

it will print out

[I@3e25a5
[D@19821f

That's the autoboxing taking place, but will still work.