Java 集合的Contains和Remove方法

package com.bjpowernode.java_learning;

import java.util.*;

​

public class D85_1_ContainsMethod {

 public static void main(String[] args) {

 //创建集合

 Collection c = new ArrayList();

 //创建两个Integer类型的对象

 Integer i1 = new Integer(10);

 //添加元素

 c.add(i1);

 //判断集合中是否包含11

 System.out.println(c.contains(i1));

 ///创建Integer类型的对象

 Integer i2 = new Integer(10);

 System.out.println(c.contains(i2));

 //这里包含了i2说明了，contains底层调用了equals方法。如果equals返回了true，就是包含

 

 Manager85 m1 = new Manager85(52,"jho");

 c.add(m1);

 Manager85 m2 = new Manager85(52,"jho");

 System.out.println(c.contains(m2));

 

 }

}

class Manager85{

 int no;

 String name;

 Manager85(int no,String name){

 this.no = no;

 this.name = name;

 }

 public boolean equals(Object o){

 if(this==o) return true;

 if(o instanceof Manager85) {

  Manager85 m = (Manager85)o;

  if(this.no==m.no && this.name.equals(m.name)){

  return true;

  }

 }

 return false;

 }

 //总结创建一个类，要重写equals方法，才能对类中的数据进行对比，否则继承原来的equals只能是对比对象的地址

}

package com.bjpowernode.java_learning;

​

import java.util.*;

​

public class D85_2_RemoveMethod {

 public static void main(String[] args) {

 //创建集合对象

 Collection c = new ArrayList();

 

 Integer i1 = new Integer(10);

 //添加元素

 c.add(i1);

 //删除

 Integer i2 = new Integer(10);

 c.remove(i2);

 

 System.out.println(c.size());

 Manager85 m1 = new Manager85(10,"ji");

 c.add(m1);

 Manager85 m2 = new Manager85(10,"ji");

 c.remove(m2);

 System.out.println(c.size());

 }

}

package com.bjpowernode.java_learning;

​

import java.util.*;

import java.lang.Iterable;

​

public class D85_3_DeepIntoRemoveMethod {

 public static void main(String[] args) {

 Collection c = new ArrayList();

 c.add(1);//这里复习了自动装箱，int类型直接转化为Integer类型

 c.add(2);

 c.add(3);

 //遍历

 Iterator it = c.iterator();

 while(it.hasNext()) {

  Object element = it.next();

  //删除

  it.remove();//通过迭代器的remove方法删除

 }

 System.out.println(c.size());

 Collection c2 = new ArrayList();

 c2.add(1);//这里复习了自动装箱，int类型直接转化为Integer类型

 c2.add(2);

 c2.add(3);

 Iterator it2 = c2.iterator();

 while(it2.hasNext()) {

  Object element = it2.next();

  c2.remove(element);

 } 

 }

}