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法律研究使用 Java 程式按值對對映進行排序
在本文中，我們將瞭解如何按值對對映進行排序。Java HashMap 是 Java 的 Map 介面的散列表實現。它是一個鍵值對集合。
以下是對它的演示：
假設我們的輸入是：
Input HashMap: Key = Java, Value = 45 Key = Scala, Value = 20 Key = Mysql, Value = 11 Key = Python, Value = 75
期望輸出是：
The HashMap after sorting is: Key = Mysql, Value = 11 Key = Scala, Value = 20 Key = Java, Value = 45 Key = Python, Value = 75
演算法
Step 1 - START Step 2 - Declare namely Step 3 - Define the values. Step 4 - Use the ‘sort’ method to sort the elements of the map. Step 5 - Use the ‘getValue’ method to fetch the values and use the ‘compareTo’ method to comare two values. Step 6 - Iterate through the hashmap, and use the ‘getKey’ method to fetch the values into ‘temp’. Use ‘temp’ as the return value. Step 7 - Display the result Step 8 - Stop
示例 1
在這裡，我們在“main”函式下繫結所有操作。
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());
}
}
}輸出
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
在這裡，我們將操作封裝到函式中，以展示面向物件的程式設計。
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());
}
}
}輸出
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
更新於：2022 年 3 月 30 日
390 次瀏覽
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