3. 练习题

代码示例

package com.baidu.www;

import java.util.TreeSet;

public class Test {
    public static void main(String[] args) {
        TreeSet treeSet = new TreeSet();
        /**
         *     final int compare(Object k1, Object k2) {
         *         return comparator==null ? ((Comparable<? super K>)k1).compareTo((K)k2)
         *             : comparator.compare((K)k1, (K)k2);
         *     }
         */
        treeSet.add(new Person());
        treeSet.add(new Person());
        treeSet.add(new Person());
        System.out.println(treeSet);
    }
}

class Person implements Comparable{
    @Override
    public int compareTo(Object o) {
        return 0;
    }
}