TreeMap custom sorting for traversal

TreeMap custom sorting for traversal

1. The first approach

/**
 * @Description：TreeMap遍历排序案例
 * @author： cyz	
 */
public class TreeMapTest {
    
    
	private static Set<String> keySet;
	public static void main(String[] args) {
    
    
	Map<String,String> map=new LinkedHashMap<String, String>();
	map.put("id", "dfsafdajfjakfljaskfj");
	map.put("name","cyz");
	map.put("value", "25");
	map.put("yap1","kaiguan1");
	System.out.println(map.toString());
	Set<String> set = map.keySet();
	//转为迭代器
	Iterator<String> iterator = set.iterator();
	while(iterator.hasNext()) {
    
    
		String next = iterator.next();
       String name = map.get(next);
       System.out.println(next+"      "+name);
	}
  /*
	*@Description :对treemap里面的数据进行排序，负数为降序
	*@第二种：构造函数中new Comparator,匿名内部类，重写compare 方法
	*@author：cyz
	*/	
	TreeMap<String,String> rf = new TreeMap<String,String>(new Comparator(){
    
    
		   @Override
		   public int compare(Object o1, Object o2) {
    
    
		    // TODO Auto-generated method stub
		    String a = (String)o1;
		    String b = (String)o2;
		    return -a.compareTo(b);
		   }
	});
	System.out.println("---------------------------下一步-------------------------");
	//Map<String,String> treemap=new TreeMap<String, String>();
	rf.putAll(map);//将集合整体放入treemap
	//使用keySet方法进行遍历
	Set<String> keySet2 = rf.keySet();
	Iterator<String> iter2 = keySet2.iterator();
	while(iter2.hasNext()) {
    
    
		String next = iter2.next();
		String name = rf.get(next);//获取key值
		System.out.println(next+"   "+name);	
	 }
  }
}

1. The second approach

/**
 * @Description:这里创建一个用户实体
 * @author Administrator
 *
 */
public class UserVo implements Comparable<UserVo>{
    
    
	
	private int age;
	private String name;
	private String sex;
	public int getAge() {
    
    
		return age;
	}

	public void setAge(int age) {
    
    
		this.age = age;
	}
	public int getSex() {
    
    
		return sex;
	}

	public void setSex(int sex) {
    
    
		this.sex = sex;
	}

	public String getName() {
    
    
		return name;
	}

	public void setName(String name) {
    
    
		this.name = name;
	}

	public UserVo(String name, int age,String sex) {
    
    
		super();
		this.age = age;
		this.name = name;
		this.sex=sex;
	}
	@Override
	public String toString() {
    
    
		return "UserVo [age=" + age + ", name=" + name + ",sex="+sex+"]";
	}
	/**
	 * 通过比较年龄升序排列
	 */
	@Override
	public int compareTo(UserVo o) {
    
    
		// TODO Auto-generated method stub
		if(age>o.age) {
    
    
			return 1;
		}else if(age<o.age) {
    
    
			return -1;
		}
		return this.age;
	}	
}

import java.util.Set;
import java.util.TreeMap;
/**
 * @第二种：UserVo实体类中实现Comparable，重写compareTo方法
 * @Description：UserVo实体类中实现Comparable，重写compareTo方法
 * @author cyz
 */
public class TestUser {
    
    
	
	public static void main(String[] args) {
    
    
		TreeMap<Object, String> treemap=new TreeMap<Object, String>();
		treemap.put(new UserVo("张三",24,"男"),"张三");
		treemap.put(new UserVo("李四",23,"男"),"李四");
		treemap.put(new UserVo("王麻子",22,"男"),"王麻子");
		treemap.put(new UserVo("李五",21,"男"),"李五");
		Set<Object> keySet = treemap.keySet();
		for (Object obj : keySet) {
    
    
			System.out.println(obj.toString());
		}
	}
}