在Java中使用示例等于()方法的映射

Java中的java.util.Map.equals()方法用于检查两个映射之间的相等性。它验证一个作为参数传递的映射的元素是否等于这个映射的元素。

语法:

boolean equals(object obj)

参数: 该方法接受一个此映射类型的参数obj，并引用要与此映射检查相等性的映射。

返回值: 如果两个对象映射的相等性成立则返回true，否则返回false。

下面的程序说明了java.util.Map.equals()方法：

程序1：

// Java code to illustrate the equals() method
import java.util.*;
  
public class Map_Demo {
    public static void main(String[] args)
    {
        // Creating an empty Map
        Map<Integer, String> map1 = new HashMap<Integer, String>();
        Map<Integer, String> map2 = new HashMap<Integer, String>();
  
        // Mapping string values to int keys
        map1.put(10, "Geeks");
        map1.put(15, "4");
        map1.put(20, "Geeks");
        map1.put(25, "Welcomes");
        map1.put(30, "You");
  
        // Mapping string values to int keys
        map2.put(10, "Geeks");
        map2.put(15, "4");
        map2.put(20, "Geeks");
        map2.put(25, "Welcomes");
        map2.put(30, "You");
  
        // Displaying the Map1
        System.out.println("First Map: "
                           + map1);
  
        // Displaying the Map2
        System.out.println("Second Map: "
                           + map2);
  
        // Checking the equality
        System.out.println("Equality: " + map1.equals(map2));
    }
}

First Map: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Second Map: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Equality: true

程序2：

// Java code to illustrate the equals() method
import java.util.*;
  
public class Map_Demo {
    public static void main(String[] args)
    {
        // Creating an empty Map
        Map<Integer, String> map1 = new HashMap<Integer, String>();
        Map<Integer, String> map2 = new HashMap<Integer, String>();
  
        // Mapping string values to int keys for map1
        map1.put(10, "Geeks");
        map1.put(15, "four");
        map1.put(20, "Geeks");
        map1.put(25, "Welcomes");
        map1.put(30, "You");
  
        // Mapping string values to int keys for map2
        map2.put(10, "Geeks");
        map2.put(15, "4");
        map2.put(20, "Geeks");
        map2.put(25, "Welcomes");
        map2.put(30, "You");
  
        // Displaying the map 1
        System.out.println("First Map: " + map1);
  
        // Displaying the map 2
        System.out.println("Second Map: " + map2);
  
        // Displaying the equality
        System.out.println("Equality: "+ map1.equals(map2));
    }
}

First Map: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=four}
Second Map: {20=Geek, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Equality: false

参考文献 : https://docs.oracle.com/javase/7/docs/api/java/util/Map.html#equals(java.lang.Object)