Java 按键排序映射

在本文章中，我们将了解如何按键对映射进行排序。Java的Map接口，java.util.Map，表示键和值之间的映射。更具体地说，Java的Map可以存储键值对。每个键与一个特定的值相连。

以下是相同的演示示例−

假设我们的输入是 −

Input map: {1=Scala, 2=Python, 3=Java}

所期望的输出将会是 –

The sorted map with the key:
{1=Scala, 2=Python, 3=Java}

步骤

Step 1 - START
Step 2 - Declare namely
Step 3 - Define the values.
Step 4 - Create a Map structure, and add values to it using the ‘put’ method.
Step 5 - Create a TreeMap of strings.
Step 6 - The Map sorts the values based on keys and stores it in TreeMap.
Step 7 - Display this on the console.
Step 8 - Stop

示例1

在这里，我们将所有操作绑定在“main”函数下。

import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
public class Demo {
   public static void main(String[] args) {
      System.out.println("The required packages have been imported");
      Map<String, String> input_map = new HashMap<>();
      input_map.put("1", "Scala");
      input_map.put("3", "Java");
      input_map.put("2", "Python");
      System.out.println("The map is defined as: " + input_map);
      TreeMap<String, String> result_map = new TreeMap<>(input_map);
      System.out.println("\nThe sorted map with the key: \n" + result_map);
   }
}

输出

The required packages have been imported
The map is defined as: {1=Scala, 2=Python, 3=Java}

The sorted map with the key:
{1=Scala, 2=Python, 3=Java}

示例2

在这里，我们将操作封装成展示面向对象编程的函数。

import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
public class Demo {
   static void sort( Map<String, String> input_map){
      TreeMap<String, String> result_map = new TreeMap<>(input_map);
      System.out.println("\nThe sorted map with the key: \n" + result_map);
   }
   public static void main(String[] args) {
      System.out.println("The required packages have been imported");
      Map<String, String> input_map = new HashMap<>();
      input_map.put("1", "Scala");
      input_map.put("3", "Java");
      input_map.put("2", "Python");
      System.out.println("The map is defined as: " + input_map);
      sort(input_map);
   }
}

输出

The required packages have been imported
The map is defined as: {1=Scala, 2=Python, 3=Java}

The sorted map with the key:
{1=Scala, 2=Python, 3=Java}