[Java] 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);
 
} 
 
}
 
}