Java 之List根据对象字段名去重复

1. 实体PersionInfo类

public class PersionInfo {
    private String name;
    private String sex;
    private int  age;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public PersionInfo(String name,String sex,int age) {
        this.name=name;
        this.sex=sex;
        this.age=age;
    }

    @Override
    public String toString() {
        return "PersionInfo [name=" + name + ", sex=" + sex + ", age=" + age
                + "]";
    }
}

1. 定义原始数据赋值

/**
 * @author Administrator
 * 
 * java去除list重复值（循环元素删除、通过HashSet删除）  
 * 
 *   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。
 *
 */
 public class MainActivity extends Activity {
    List<PersionInfo> lists=new ArrayList<PersionInfo>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        PersionInfo info=new PersionInfo("IMCC消化科病房", "消化科", 13);
        PersionInfo info1=new PersionInfo("IMCC消化科病房", "消化科",13);
        PersionInfo info2=new PersionInfo("消化科病房", "消化内科科", 14);
        PersionInfo info3=new PersionInfo("消化科病房(南院", "消化科", 15);
        lists.add(info);
        lists.add(info1);
        lists.add(info2);
        lists.add(info3);
        remove(lists);  
    }

    /**
     * 
     * 去重
     */

    private void remove(List<PersionInfo> lists){
        HashSet<NewPersionInfo> hashSet=new HashSet<NewPersionInfo>();
        //需要保留的字段
        for (int i = 0; i < lists.size(); i++) {
            String name = lists.get(i).getName();
            String sex = lists.get(i).getSex();
            //重写组合并赋值
            NewPersionInfo newPersionInfo=new NewPersionInfo();
            newPersionInfo.setName(name);
            newPersionInfo.setSex(sex);
            hashSet.add(newPersionInfo);
        }
        //添加到新的集合中
        List<NewPersionInfo> list=new ArrayList<NewPersionInfo>();
        list.clear();
        list.addAll(hashSet);
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i).toString()+"===");
        }

    }
}

3.获取新的NewPersionInfo实体类

public class NewPersionInfo {

    private String name;
    private String sex;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }


    /**
     * 根据对象的sex去重
     */
    @Override
    public boolean equals(Object object) {
        NewPersionInfo info=(NewPersionInfo) object;
        return sex.equals(info.sex);
    }
    /**
     * 将字段名换成hashCode
     */
    @Override
    public int hashCode() {  
        //赋值比较 
        String names=sex;
        return names.hashCode();
    }
    @Override
    public String toString() {
        return "NewPersionInfo [name=" + name + ", sex=" + sex + "]";
    }


}