TreeSet的练习（使用比较器）--笔记 - 黑马程序员技术交流社区

<div>import java.util.Comparator;
import java.util.TreeSet;
import com.heima.bean.Student;
/*
* TreeSet练习题
*
* 要求使用 Comparable进行排序，
* 先按照语文成绩排序，分数高的在前面
* 语文成绩一样的，按照数学成绩排序，分数大的在前面
* 数学成绩一样的，按照英语成绩排序，分数大的在前面
*
* 分数都相同，按照姓名的自然顺序进行排序
*
* 下面参数意义：姓名，语文成绩，数学成绩，英语成绩
* new Student("lingqingxia", 89, 95, 100)
* new Student("lingqing", 89, 96, 98)
* new Student("lingqing", 89, 96, 100)
* new Student("lingqing", 69, 98, 70)
* new Student("lingqingxia", 100, 95, 100)
* new Student("zhaosi", 100, 95, 100)
*/
public class Test {
public static void main(String[] args) {
TreeSet<Student> ts = new TreeSet<>(new Comparator<Student>() {
@Override
public int compare(Student s1, Student s2) {
//int num = s2.getSum() - s1.getSum();
int num = s2.getChinese() -s1.getChinese();
int num1 = num == 0 ? (s2.getMath() -s1.getMath()) :num;
int num2 = num == 0 ? (s2.getEnglish() -s1.getEnglish()) :num1;
//int num3 = num == 0 ? (s2.getEnglish() -s1.getEnglish()) :num2;
return num2;
}
});
ts.add(new Student("lingqingxia", 89, 95, 100));
ts.add(new Student("lingqing", 89, 96, 98));
ts.add(new Student("lingqing", 89, 96, 100));
ts.add(new Student("lingqing", 69, 98, 70));
ts.add(new Student("lingqingxia", 100, 95, 100));
ts.add(new Student("zhaosi", 100, 95, 100));
for (Student s : ts) {
System.out.println(s);
}
}
}</div><div>=============================================自定义Student类</div><div><div class="blockcode"><blockquote>package com.heima.bean;
public class Student extends Person {
private String name;
private int chinese;
private int math;
private int english;
private int sum;
public Student() {
super();
}
public Student(String name, int chinese, int math, int english) {
super();
this.name = name;
this.chinese = chinese;
this.math = math;
this.english = english;
//this.sum = this.chinese+this.english+this.math;
}
/*public int getSum (){
return sum;
}
*/
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getChinese() {
return chinese;
}
public void setChinese(int chinese) {
this.chinese = chinese;
}
public int getMath() {
return math;
}
public void setMath(int math) {
this.math = math;
}
public int getEnglish() {
return english;
}
public void setEnglish(int english) {
this.english = english;
}
@Override
public String toString() {
return "Student [name=" + name + ", chinese=" + chinese + ", math="
+ math + ", english=" + english + "]";
}
@Override
public int hashCode() {
final int prime = 31;
int result = super.hashCode();
result = prime * result + chinese;
result = prime * result + english;
result = prime * result + math;
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (!super.equals(obj))
return false;
if (getClass() != obj.getClass())
return false;
Student other = (Student) obj;
if (chinese != other.chinese)
return false;
if (english != other.english)
return false;
if (math != other.math)
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
}

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