TreeSet第二种排序方法（比较器排序）

1. 

    

    

2. 

    

    

3. 代码实现：import java.util.Comparator;
   import java.util.TreeSet;
   
   public class TreeSet排序方法 {
       public static void main(String[] args) {
           TreeSet<String> treeSet=new TreeSet<>(new Comparator<String>() {
               @Override
               public int compare(String o1, String o2) {
                   int i=o1.length()-o2.length();
                 i=i==0?o1.compareTo(o2):i;
                   return i;
               }
           });
           treeSet.add("a");
           treeSet.add("ab");
           treeSet.add("df");
           treeSet.add("aweq");
           System.out.println(treeSet);
       }
   }

4. TreeSet的案例
5. 代码实现：

    

    

   mport java.util.TreeSet;
   
   public class treeset练习 {
       public static void main(String[] args) {
           student2 s1 = new student2("张三", 23, 90, 99, 50);
           student2 s2 = new student2("李四", 24, 90, 98, 50);
           student2 s3 = new student2("王五", 25, 95, 100, 30);
           student2 s4 = new student2("赵六", 26, 60, 99, 70);
           student2 s5 = new student2("钱七", 26, 70, 80, 70);
           TreeSet<student2> treeSet=new TreeSet<>();
           treeSet.add(s1);
           treeSet.add(s2);
           treeSet.add(s3);
           treeSet.add(s4);
           treeSet.add(s5);
          // System.out.println(treeSet);//直接打印未定义排序方法会报错
           for (student2 student2 : treeSet) {
               System.out.println(student2);
           }
       }
   }
   class student2 implements Comparable<student2> {
       private String name;
       private  int age;
       private int chinese;
       private int math;
       private  int english;
   
       public student2(String name, int age, int chinese, int math, int english) {
           this.name = name;
           this.age = age;
           this.chinese = chinese;
           this.math = math;
           this.english = english;
       }
   
       public String getName() {
           return name;
       }
   
       public void setName(String name) {
           this.name = name;
       }
   
       public int getAge() {
           return age;
       }
   
       public void setAge(int age) {
           this.age = age;
       }
   
       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 "student2{" +
                   "name='" + name + '\'' +
                   ", age=" + age +
                   ", chinese=" + chinese +
                   ", math=" + math +
                   ", english=" + english +
                   '}';
       }
   
       @Override
       public int compareTo(student2 o) {
           int sum1=this.getChinese()+this.math+this.getEnglish();
           int sum2=o.getChinese()+o.math+o.getEnglish();
           int i=sum1-sum2;
           //比较两者总分
           i=i==0?this.getChinese()-o.getChinese():i;
           //总分一样按照语文排序
              i=i==0?this.getMath()-o.getMath():i;
              //    //数学一样按照语文排序
              i=i==0?this.getEnglish()-this.getEnglish():i;
              i=i==0?this.getAge()-o.getAge():i;
              i=i==0?this.getName().compareTo(o.getName()):i;
           return i;
       }
   }

6. 小结：

   

    

    

7.  

   如果方式1和方式2同时存在，使用方式2的方法