Map<自定义类，v>=new TreeMap(), 自定义类自定义compareTo方法排序
Topic source
@Override
public boolean equals(Object o) {
if(o instanceof Student) {
Student s=(Student) o;
return Objects.equals(this.name, s.getName()) && this.age==s.getAge() && this.score==s.getScore();
}
return false;
}
@Override
public int hashCode() {
return Objects.hash(this.name, this.age, this.score);
}
- 1
净净一隅
public class Student extends Person implements Comparable<Student>{
private int score=0;
public Student(String name,int age,int score) {
super(name,age);
this.score=score;
}
public Student(String name,int score) {
super(name);
this.score=score;
}
public int getScore() {
return score;
}
public void setScore(int score) {
this.score = score;
}
public int compareTo(Student other) {
if(this.score==other.score && this.name.equals(other.getName()) && this.age==other.getAge())
{
return 0;
}
//return this.getName().compareTo(other.getName()); //姓名首字母升序排序
//return other.getName().compareTo(this.getName()); //姓名首字母降序排序
//return other.getScore()-this.getScore(); //分数降序排序
return this.getScore()>other.getScore() ? 1:-1; //分数升序排序
}
public String toString() {
return "Student[name: "+this.name+", age:"+this.age+", score:"+this.score+"]\n";
}
public static void main(String[] args) {
Map<Student,Integer> map=new TreeMap<>();
map.put(new Student("Apple", 19,33), 1);
map.put(new Student("Orange", 19,33), 2);
map.put(new Student("Banana", 23,44), 3);
map.put(new Student("Orange", 18,33), 4);
log.info(new Student("Apple", 19,33).hashCode()); //871441287
log.info(new Student("Orange", 20,33).hashCode()); //1221078458
log.info(new Student("Apple",19,33).equals(new Student("Orange", 20,33))); //false
log.info(map.get(new Student("Orange", 20,33))); //null
log.info(map.get(new Student("Apple", 19,33))); //1
log.info(map);
/*{Student[name: Orange, age:18, score:33]=4,
* Student[name: Orange, age:19, score:33]=2,
* Student[name: Apple, age:19, score:33]=1,
* Student[name: Banana, age:23, score:44]=3}
*/
}
}