https://www.jianshu.com/p/2dcff3634326
参考上面的文章，对TreeMap做了一个简单的测试

[ractest@stbm000020-vm1 WalkAlert]$ cat ./src/test_package/treeMapTest.java
package test_package;

import java.util.*;

public class treeMapTest {
  public static void main(String[] args){
    TreeMap<String,Integer> treeMap = new TreeMap<String,Integer>();
    treeMap.put("wang",3);
    treeMap.put("li",4);
    System.out.println(treeMap.get("wang"));
    System.out.println(treeMap.get("li"));
  }

}