java----TreeSet实现自定义排序

1,构造方法：
TreeSet(Comparator<? super E> comparator)
构造一个新的空 TreeSet，它根据指定比较器进行排序。自定义排序
2,Comparator 接口：
int compare(T o1, T o2) 比较用来排序的两个参数。
boolean equals(Object obj) 指示某个其他对象是否“等于”此 Comparator
3,实例:
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import java.util.Comparator;

public class MyComparator implements Comparator {
@Override
public int compare(String o1, String o2) {
return o1.compareTo(o2);
}
}

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import java.util.Comparator;

public class StuComparator implements Comparator{
@Override
public int compare(Stu o1, Stu o2) {
int num=o1.getName().compareTo(o2.getName());
return num!=0?num:(o1.getAge()<o2.getAge()?1:(o1.getAge()==o2.getAge()?0:-1));
}
}

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public class Stu {
private String name;
private int age;

public Stu() {
}

public Stu(String name, int age) {
    this.name = name;
    this.age = age;
}

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;
}

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    if (!(o instanceof Stu)) return false;

    Stu stu = (Stu) o;

    if (getAge() != stu.getAge()) return false;
    return getName().equals(stu.getName());
}

@Override
public int hashCode() {
    int result = getName().hashCode();
    result = 31 * result + getAge();
    return result;
}

@Override
public String toString() {
    return "Stu{" +
            "name='" + name + '\'' +
            ", age=" + age +
            '}';
}

}

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import java.util.TreeSet;

public class TreeSetDemo2 {
public static void main(String[] args){
//根据TreeSet的某个构造方法TreeSet(Comparator<? super E> comparator)
// 构造一个新的空的TreeSet,根据制定比较器进行排序
MyComparator myComparator=new MyComparator();
TreeSet test=new TreeSet(myComparator);
test.add(“susan”);
test.add(“peter”);
test.add(“jerry”);
test.add(“jerry”);//重复的元素不出现
for(String item:test){
System.out.println(“集合元素:”+item);
}
System.out.println("=自定义类型===");
StuComparator stuComparator=new StuComparator();
TreeSet test2=new TreeSet(stuComparator);
Stu stu1=new Stu(“jerry”,20);
Stu stu2=new Stu(“susan”,19);
Stu stu3=new Stu(“peter”,18);
Stu stu4=new Stu(“jerry”,18);
test2.add(stu1);
test2.add(stu2);
test2.add(stu3);
test2.add(stu4);
for(Stu s:test2){
System.out.println(“集合元素:”+s);
}
}
}

java----TreeSet实现自定义排序

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