基础——TreeSet练习0523
package cn.mmc.day14;import java.util.*;/*当元素自身不具备比较性，或者具备的比较性不是所需要的。这时需要让容器自身具备比较性。定义了比较器，将比较器对象作为参数传递给TreeSet集合的构造函数。当两种排序都存在时，以比较器为主。定义一个类，实现Comparator接口，覆盖compare方法。*/public class TreeSetExcise {public static void main(String[] args) {TreeSet ts = new TreeSet();ts.add(new Student("lisi02",22));ts.add(new Student("lisi02",21));ts.add(new Student("lisi007",20));ts.add(new Student("lisi09",19));ts.add(new Student("lisi06",18));ts.add(new Student("lisi06",18));ts.add(new Student("lisi007",29));//ts.add(new Student("lisi007",20));//ts.add(new Student("lisi01",40));Iterator it = ts.iterator();while(it.hasNext()){Student stu = (Student)it.next();System.out.println(stu.getName()+"..."+stu.getAge());}}}class MyCompare implements Comparator{public int compare(Object o1,Object o2){Student s1 = (Student)o1;Student s2 = (Student)o2;int num = s1.getName().compareTo(s2.getName());if(num==0)//当姓名相同时，在判断年龄{return new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));/*if(s1.getAge()>s2.getAge())return 1;if(s1.getAge()==s2.getAge())return 0;return -1;*/}return num;}}/*练习：按照字符串长度排序。字符串本身具备比较性。但是它的比较方式不是所需要的。这时就只能使用比较器。*/class TreeSetTest{public static void main(String[] args) {TreeSet ts = new TreeSet(new StrLenComparator());ts.add("abcd");ts.add("cc");ts.add("cba");ts.add("aaa");ts.add("z");ts.add("hahaha");Iterator it = ts.iterator();while(it.hasNext()){System.out.println(it.next());}}}class StrLenComparator implements Comparator{public int compare(Object o1,Object o2){String s1 = (String)o1;String s2 = (String)o2;/*if(s1.length()>s2.length())return 1;if(s1.length()==s2.length())return 0;*/int num = new Integer(s1.length()).compareTo(new Integer(s2.length()));if(num==0)return s1.compareTo(s2);return num;}}