Java 程序按值对 Map 进行排序
javacampus interviewserver side programmingprogramming更新于 2024/8/8 19:34:00
在本文中，我们将了解如何按值对 Map 进行排序。Java HashMap 是 Java Map 接口的基于哈希表的实现。它是键值对的集合。
下面是相同的演示 −
假设我们的输入是 −
输入HashMap: Key = Java, Value = 45 Key = Scala, Value = 20 Key = Mysql, Value = 11 Key = Python, Value = 75
期望输出的将是 −
排序后的HashMap为: Key = Mysql, Value = 11 Key = Scala, Value = 20 Key = Java, Value = 45 Key = Python, Value = 75
算法
步骤1 - 开始 步骤2 - 声明 步骤3 - 定义值。 步骤4 - 使用‘sort’方法对映射中的元素进行排序。 步骤5 - 使用‘getValue’方法获取值，并使用‘compareTo’方法比较两个值。 步骤 6 - 遍历哈希图，并使用‘getKey’方法将值放入‘temp’中。使用‘temp’作为返回值。 步骤 7 - 显示结果 步骤 8 - 停止
示例 1
在这里，我们将所有操作都绑定在‘main’函数下。
import java.util.*;
import java.lang.*;
public class Demo {
public static HashMap<String, Integer> sort(HashMap<String, Integer> input_map){
List<Map.Entry<String, Integer> > list =
new LinkedList<Map.Entry<String, Integer> >(input_map.entrySet());
Collections.sort(list, new Comparator<Map.Entry<String, Integer> >() {
public int compare(Map.Entry<String, Integer> o1,
Map.Entry<String, Integer> o2){
return (o1.getValue()).compareTo(o2.getValue());
}
});
HashMap<String, Integer> temp = new LinkedHashMap<String, Integer>();
for (Map.Entry<String, Integer> aa : list) {
temp.put(aa.getKey(), aa.getValue());
}
return temp;
}
public static void main(String[] args){
HashMap<String, Integer> input_map = new HashMap<String, Integer>();
input_map.put("Java", 45);
input_map.put("Scala", 20);
input_map.put("Mysql", 11);
input_map.put("Python", 75);
System.out.println("The HashMap is defined as:");
for (Map.Entry<String, Integer> element : input_map.entrySet()) {
System.out.println("Key = " + element.getKey() + ", Value = " + element.getValue());
}
Map<String, Integer> result_map = sort(input_map);
System.out.println("\nThe HashMap after sorting is:");
for (Map.Entry<String, Integer> element : result_map.entrySet()) {
System.out.println("Key = " + element.getKey() + ", Value = " + element.getValue());
}
}
}
输出
The HashMap is defined as: Key = Java, Value = 45 Key = Scala, Value = 20 Key = Mysql, Value = 11 Key = Python, Value = 75 The HashMap after sorting is: Key = Mysql, Value = 11 Key = Scala, Value = 20 Key = Java, Value = 45 Key = Python, Value = 75
示例 2
在这里，我们将操作封装成展现面向对象编程的函数。
import java.util.*;
import java.lang.*;
public class Demo {
public static void main(String[] args){
HashMap<String, Integer> input_map = new HashMap<String, Integer>();
input_map.put("Java", 45);
input_map.put("Scala", 20);
input_map.put("Mysql", 11);
input_map.put("Python", 75);
System.out.println("The HashMap is defined as:");
for (Map.Entry<String, Integer> element : input_map.entrySet()) {
System.out.println("Key = " + element.getKey() + ", Value = " + element.getValue());
}
List<Map.Entry<String, Integer> > list =
new LinkedList<Map.Entry<String, Integer> >(input_map.entrySet());
Collections.sort(list, new Comparator<Map.Entry<String, Integer> >() {
public int compare(Map.Entry<String, Integer> o1,
Map.Entry<String, Integer> o2){
return (o1.getValue()).compareTo(o2.getValue());
}
});
HashMap<String, Integer> result_map = new LinkedHashMap<String, Integer>();
for (Map.Entry<String, Integer> aa : list) {
result_map.put(aa.getKey(), aa.getValue());
}
System.out.println("\nThe HashMap after sorting is:");
for (Map.Entry<String, Integer> element : result_map.entrySet()) {
System.out.println("Key = " + element.getKey() + ", Value = " + element.getValue());
}
}
}
输出
The HashMap is defined as: Key = Java, Value = 45 Key = Scala, Value = 20 Key = Mysql, Value = 11 Key = Python, Value = 75 The HashMap after sorting is: Key = Mysql, Value = 11 Key = Scala, Value = 20 Key = Java, Value = 45 Key = Python, Value = 75
