如何编写通用方法来交换数组中项目的值？

Question

I am trying to get this code to work. Most of the code was provided as a question but I just keep getting error after error that I simply to not understand.

package generic.collections;
import java.util.ArrayList;

public static void <T> T swap(Collection<T>, T x, T y) {  
    T temp = a[x]; 
    a[x] = a[y]; 
    a[y] = temp;  
    } 
}

Answer 1

Your definition is off, first a void method can't return a T . An array is not a Collection . And x and y should be int (s). Like,

public static <T> void swap(T[] a, int x, int y) {
    T temp = a[x];
    a[x] = a[y];
    a[y] = temp;
}