关于list的indexOf与equals的联系

public class Product { private int id; private String name; public Product(int id,String name){ this.id = id; this.name = name; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public boolean equals(Product p){ if (this.id == p.getId()) { return true; } else { return false; } }}

 

 

import java.util.ArrayList;import java.util.List;public class ProductApp { public static void main(String[] args) { Product p1 = new Product(1,"a"); Product p2 = new Product(2,"b"); Product p3 = new Product(3,"c"); Product p2_ = new Product(2,"b"); List<Product> list = new ArrayList<Product>(); list.add(p1); list.add(p2); list.add(p3); for (int i = 0; i < list.size(); i++) { System.out.println(p2_.equals(list.get(i))); } System.out.println(list.indexOf(p2_)); }} 

 

false
true
false
-1

public boolean equals(Product p){ if (this.id == p.getId()) { return true; } else { return false; }// Product p = (Product)o;// if (this.id == p.getId()) {// return true;// } else {// return false;// } }

false
true
false
1

 

 

public int indexOf(Object o) { if (o == null) { for (int i = 0; i < size; i++) if (elementData[i]==null) return i; } else { for (int i = 0; i < size; i++) if (o.equals(elementData[i])) return i; } return -1;}

 

 

 

来源：http://topic.csdn.net/u/20100705/11/719E49EA-D94E-4EB7-B5DE-7DA6E1EF9B6E.html