TreeSet的总结

来源：互联网发布：汤姆大叔javascript 编辑：程序博客网时间：2024/05/16 08:42

//TreeSet有两种顺序排列：自然顺序和自定义顺序

import java.util.TreeSet;

public class TreeSetTest

{

public static void main(String[] args)

{

TreeSet set = new TreeSet();

set.add("C");

set.add("A");

set.add("B");

set.add("E");

set.add("F");

set.add("D");

System.out.println(set);

}

输出结果：[A, B, C, D, E, F]

//自定义TreeSet排序Compatator，以及用迭代遍历

import java.util.Comparator;

import java.util.Iterator;

import java.util.TreeSet;

public class TreeSetTest2

{

public static void main(String[] args)

{

TreeSet set = new TreeSet(new PersonComparator());

Person p1 = new Person(10);

Person p2 = new Person(20);

Person p3 = new Person(30);

Person p4 = new Person(40);

set.add(p1);

set.add(p2);

set.add(p3);

set.add(p4);

for(Iterator iter = set.iterator(); iter.hasNext();)

{

Person p = (Person)iter.next();

System.out.println(p.score);

}

class Person

{

int score;

public Person(int score)

{

this.score = score;

}

public String toString()

{

return String.valueOf(this.score);

}

class PersonComparator implements Comparator

{

public int compare(Object arg0, Object arg1)

{

Person p1 = (Person) arg0;

Person p2 = (Person) arg1;

return p2.score - p1.score;

}

//在compare方法中两个数值比较：如果小于则升序，等于则自然顺序，大于则降序

import java.util.Comparator;

import java.util.Iterator;

import java.util.TreeSet;

public class TreeSetTest3

{

public static void main(String[] args)

{

TreeSet set = new TreeSet(new MyComparator());

set.add("C");

set.add("A");

set.add("B");

set.add("E");

set.add("a");

set.add("F");

set.add("D");

for(Iterator iter = set.iterator(); iter.hasNext();)

{

String value = (String)iter.next();

System.out.println(value);

}

class MyComparator implements Comparator

{

public int compare(Object arg0, Object arg1)

{

String s1 = (String)arg0;

String s2 = (String)arg1;

return s2.compareTo(s1);

}