Use the get() method of the Hashtable class in Java to obtain the value corresponding to the key

Use the get() method of the Hashtable class in Java to obtain the value corresponding to the key

Hashtable is a commonly used data structure class in Java, which implements a hash table of key-value pairs. It calculates the storage location by key, so that the corresponding value can be found directly through the key, thereby enabling fast access and storage of data.

In the Hashtable class, we can use the get() method to obtain the value corresponding to a key. The syntax of the get() method is as follows:

public V get(Object key)

where key is the key to be found, and V is the type of value.

The following is a sample code that uses the get() method of the Hashtable class to obtain the value corresponding to the key:

import java.util.Hashtable;

public class HashtableExample {
    public static void main(String[] args) {
        Hashtable<String, String> hashtable = new Hashtable<>();
        
        // 添加键值对
        hashtable.put("name", "Tom");
        hashtable.put("age", "20");
        hashtable.put("gender", "male");
        
        // 获取键对应的值
        String name = hashtable.get("name");
        String age = hashtable.get("age");
        String gender = hashtable.get("gender");
        
        // 输出结果
        System.out.println("name: " + name);
        System.out.println("age: " + age);
        System.out.println("gender: " + gender);
    }
}

In the above code, we first create a Hashtable object, and then use put () method adds three key-value pairs to the Hashtable. The keys are "name", "age" and "gender", and the corresponding values ​​are "Tom", "20" and "male" respectively.

Next, we use the get() method to obtain the values ​​corresponding to the keys "name", "age" and "gender" respectively, and assign these values ​​to the corresponding variables.

Finally, we print out these values ​​through the output statement, and we can see that the output result is:

name: Tom
age: 20
gender: male

It means that the get() method successfully obtained the value corresponding to the key.

It should be noted that when using the get() method to obtain the value corresponding to a key, the key needs to be passed to the get() method as a parameter. If the specified key does not exist in the Hashtable, the get() method will return null.

In addition, for the Hashtable object, its keys and values ​​can be null. If you want to store a null value, you can directly pass null as the value to the put() method. However, for keys, if null is passed as the key, a NullPointerException will be thrown.

The article ends here. By using the get() method of the Hashtable class, we can easily obtain the value corresponding to the key, realizing fast access and storage of data. I hope this article will help you understand the use of the Hashtable class.

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