Java Example - Collection Output

The following example demonstrates how to use the tMap.keySet(), tMap.values() and tMap.firstKey() methods of the Java Util class to output the set elements:

/*
 author by w3cschool.cc
 Main.java
 */

import java.util.*;

public class Main{
   public static void main(String[] args) {
      System.out.println("TreeMap 实例！\n");
      TreeMap tMap = new TreeMap();
      tMap.put(1, "Sunday");
      tMap.put(2, "Monday");
      tMap.put(3, "Tuesday");
      tMap.put(4, "Wednesday");
      tMap.put(5, "Thursday");
      tMap.put(6, "Friday");
      tMap.put(7, "Saturday");
      System.out.println("TreeMap 键：" 
      + tMap.keySet());
      System.out.println("TreeMap 值：" 
      + tMap.values());
      System.out.println("键为 5 的值为: " + tMap.get(5)+ "\n");
      System.out.println("第一个键: " + tMap.firstKey() 
      + " Value: " 
      + tMap.get(tMap.firstKey()) + "\n");
      System.out.println("最后一个键: " + tMap.lastKey() 
	  + " Value: "+ tMap.get(tMap.lastKey()) + "\n");
      System.out.println("移除第一个数据: " 
      + tMap.remove(tMap.firstKey()));
      System.out.println("现在 TreeMap 键为: " 
      + tMap.keySet());
      System.out.println("现在 TreeMap 包含: " 
      + tMap.values() + "\n");
      System.out.println("移除最后一个数据: " 
      + tMap.remove(tMap.lastKey()));
      System.out.println("现在 TreeMap 键为: " 
      + tMap.keySet());
      System.out.println("现在 TreeMap 包含: " 
      + tMap.values());
   }
}

The above code runs the output The result is:

TreeMap 实例！

TreeMap 键：[1, 2, 3, 4, 5, 6, 7]
TreeMap 值：[Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday]
键为 5 的值为: Thursday

第一个键: 1 Value: Sunday

最后一个键: 7 Value: Saturday

移除第一个数据: Sunday
现在 TreeMap 键为: [2, 3, 4, 5, 6, 7]
现在 TreeMap 包含: [Monday, Tuesday, Wednesday, Thursday, Friday, Saturday]

移除最后一个数据: Saturday
现在 TreeMap 键为: [2, 3, 4, 5, 6]
现在 TreeMap 包含: [Monday, Tuesday, Wednesday, Thursday, Friday]

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