Java IdentityHashMap get() 方法

2025年1月7日 | 阅读 2 分钟

Java IdentityHashMap 的 get(Object key) 方法用于在调用的 IdentityHashMap 中获取与指定键关联的值，如果键未与任何值关联，则返回 null。

语法

参数

key - 要查找其关联值的键。

与指定键关联的值，如果键未与任何值关联，则返回 null。

示例 1

import java.util.IdentityHashMap;

public class IdentityHashMapGetExample1 {
    public static void main(String[] args) {
   //Creating an object of IdentityHashMap class
   IdentityHashMap<String,Integer> map = new IdentityHashMap<String,Integer>(6);
   
   //Putting key-value pairs inside map
   map.put("Java", 1);
   map.put("is", 2);
   map.put("the", 3);
   map.put("best", 4);
   map.put("programming", 5);
   map.put("language", 6);
   
   //Creating an object of Object class, to be used as key
   Object obj = new Object();
   obj = "Java";
   
   //Getting the value of the specified key
   System.out.println(map.get(obj));
   System.out.println(map.get("best"));
   System.out.println(map.get("Object"));
   
}
}

输出

1
4
null

示例 2

import java.util.IdentityHashMap;

public class IdentityHashMapGetExample2 {
    public static void main(String[] args) {
   //Creating an object of IdentityHashMap class
   IdentityHashMap<Integer,String> map = new IdentityHashMap<Integer,String>(6);
   
   //Putting key-value pairs inside map
   map.put(1, "Java");
   map.put(2, "is");
   map.put(3, "the");
   map.put(4, "best");
   map.put(5, "programming");
   map.put(6, "language");
   
   //Creating an object of Object class, to be used as key
   Object obj = new Object();
   obj = 1;
   
   //Getting the value of the specified key
   System.out.println(map.get(obj));
   System.out.println(map.get(4));
   System.out.println(map.get(8));

}
}

输出

Java
best
null

示例 3

import java.util.IdentityHashMap;

class Student{
    private int roll;
    private String name;
    private int standard;
    
    public Student(int roll,String name,int standard){
        this.roll = roll;
        this.name = name;
        this.standard = standard;
    }
    
    public String disp(){
        return roll+" "+name+" "+standard;
    }
}

public class IdentityHashMapGetExample3 {
    public static void main(String[] args) {
        
        //Creating Objects of Student class
        Student stud1 = new Student(1 ,"Ram ",10);
        Student stud2 = new Student(2 ,"Shyam ",10);
        Student stud3 = new Student(3 ,"Aman ",12);
        Student stud4 = new Student(4 ,"Harsh ",12);
        Student stud5 = new Student(5 ,"Shivam",11);
        
        //Creating an instance of IdentityHashMap
        IdentityHashMap<Integer,Student> map = new IdentityHashMap<Integer,Student>(5);
                
        //Inserting the Student class objects into IdentityHashMap
        map.put(1,stud1);
        map.put(2,stud2);
        map.put(3,stud3);
        map.put(4,stud4);        

        //Getting the value linked with the specified key
        System.out.println(map.get(1));
        System.out.println(map.get(2));
        System.out.println(map.get(4));
        System.out.println(map.get(5));
}
}

输出

[email protected]
[email protected]
[email protected]
null

下一主题Java-identityhashmap-equals-method

Java IdentityHashMap get() 方法

语法

参数

返回

示例 1

示例 2

示例 3

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Java IdentityHashMap get() 方法

语法

参数

返回

示例 1

示例 2

示例 3

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