list集合去除重复对象

对象重复是指对象里面的变量的值都相等，并不定是地址。list集合存储的类型是基础类型还比较好办，直接把list集合转换成set集合就会自动去除。

当set集合存储的是对象类型时，需要在对象的实体类里面重写public boolean equals(Object obj) {} 和 public int hashCode() {} 两个方法。

实体类

public class Student {public String id;public String name;public Student() {}public Student(String id,String name) {this.id = id;this.name = name;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}@Overridepublic boolean equals(Object obj) {Student s=(Student)obj; return id.equals(s.id) && name.equals(s.name); }@Overridepublic int hashCode() {String in = id + name;return in.hashCode();}}

测试类

import java.util.ArrayList;import java.util.HashSet;import java.util.List;import java.util.Set;public class QuSame {public static void main(String[] args) {List<Student> stu = new ArrayList<Student>();stu.add(new Student("1","yi"));stu.add(new Student("3","san"));stu.add(new Student("3","san"));stu.add(new Student("2","er"));stu.add(new Student("2","er"));//set集合保存的是引用不同地址的对象Set<Student> ts = new HashSet<Student>();ts.addAll(stu);for (Student student : ts) {System.out.println(student.getId()+"-"+student.getName());}}}