Java 示例 - 打印集合

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  问题描述

  如何打印收藏？
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  解决方案

  以下示例如何使用 Java Util 类的 tMap.keySet()、tMap.values() 和 tMap.firstKey() 方法打印集合。

  
  import java.util.*;
  public class TreeExample{
     public static void main(String[] args) {
        System.out.println("Tree Map Example!\n");
        TreeMap <Integer, String>tMap = new TreeMap<Integer, String>();
        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("Keys of tree map: " + tMap.keySet());
        System.out.println("Values of tree map: " + tMap.values());
        System.out.println("Key: 5 value: " + tMap.get(5)+ "\n");
        System.out.println(
           "First key: " + tMap.firstKey() + " Value: " + tMap.get(tMap.firstKey()) + "\n");
        System.out.println(
           "Last key: " + tMap.lastKey() + " Value: "+ tMap.get(tMap.lastKey()) + "\n");
        System.out.println("Removing first data: " + tMap.remove(tMap.firstKey()));
        System.out.println("Now the tree map Keys: " + tMap.keySet());
        System.out.println("Now the tree map contain: " + tMap.values() + "\n");
        System.out.println("Removing last data: " + tMap.remove(tMap.lastKey()));
        System.out.println("Now the tree map Keys: " + tMap.keySet());
        System.out.println("Now the tree map contain: " + tMap.values());
     }
  }
  

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  结果

  上面的代码示例将产生以下结果。

  
  C:\collection>javac TreeExample.java
  C:\collection>java TreeExample
  Tree Map Example!
  Keys of tree map: [1, 2, 3, 4, 5, 6, 7]
  Values of tree map: [Sunday, Monday, Tuesday, Wednesday, 
  Thursday, Friday, Saturday]
  Key: 5 value: Thursday
  First key: 1 Value: Sunday
  Last key: 7 Value: Saturday
  Removing first data: Sunday
  Now the tree map Keys: [2, 3, 4, 5, 6, 7]
  Now the tree map contain: [Monday, Tuesday, Wednesday,
  Thursday, Friday, Saturday]
  Removing last data: Saturday
  Now the tree map Keys: [2, 3, 4, 5, 6]
  Now the tree map contain: [Monday, Tuesday, Wednesday,
  Thursday, Friday]
  C:\collection>
  

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