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classUser{String name;int age;publicUser(){}publicUser(String name,int age){this.name = name;this.age = age;}public boolean equals(Object obj){if(this== obj){returntrue;}//instanceof作用：判断前面的对象是不是后面对象的类型 boolean b = obj instanceof User;if(b){//obj向下转型为User对象User u =(User)obj;if(this.age == u.age &&this.name.equals(u.name)){returntrue;}else{returnfalse;}}else{returnfalse;}}//复写User的hashCodepublicint hashCode(){int result =17; result =31* result + age; result =31* result +name.hashCode();return result;}}import java.util.*;publicclassTest{publicstaticvoid main(String args []){User u =newUser("zhangsan",12);HashMap<User,String>map=newHashMap<User,String>();map.put(u,"abc");//通过计算键的hashcode来判断有没有存在相应的值String s =map.get(newUser("zhangsan",12));System.out.println(s);}}classUser{String name;int age;publicUser(){}publicUser(String name,int age){this.name = name;this.age = age;}public boolean equals(Object obj){if(this== obj){returntrue;}//instanceof作用：判断前面的对象是不是后面对象的类型 boolean b = obj instanceof User;if(b){//obj向下转型为User对象User u =(User)obj;if(this.age == u.age &&this.name.equals(u.name)){returntrue;}else{returnfalse;}}else{returnfalse;}}//复写User的hashCodepublicint hashCode(){int result =17; result =31* result + age; result =31* result +name.hashCode();return result;}publicString toString(){String result ="age:"+age+","+"name:"+ name;return result; }}import java.util.*;publicclassTest{publicstaticvoid main(String args []){User u =newUser("zhangsan",12);System.out.println(u);}}标签：
原文地址：http://www.cnblogs.com/arroneve/p/5815481.html
