如何在Android中为一个类的每个实例获取唯一的索引？

public class MyClass {
    private static int instanceCount = 0;
    private int index;

    public MyClass() {
        index = instanceCount;
        instanceCount++;
    }

    public int getIndex() {
        return index;
    }
}

import java.util.UUID;

public class MyClass {
    private UUID index;

    public MyClass() {
        index = UUID.randomUUID();
    }

    public UUID getIndex() {
        return index;
    }
}