Java 中的字典删除()方法

原文:https://www . geesforgeks . org/dictionary-remove-method-in-Java/

字典类的 remove() 方法接受一个键作为参数，并移除映射到该键的相应值。

语法:

public abstract V remove(Object key)

参数:该函数接受一个参数键，该键表示要从字典中删除的键及其映射。

返回值:该函数返回映射到键的值，如果键没有映射，则返回空值。

异常:如果作为参数传递的键为空，则函数不抛出空指针异常。

下面的程序说明了Java . util . dictionary . remove()方法的使用:

程序 1:

// Java Program to illustrate
// java.util.Dictionary.remove() method

import java.util.*;

class GFG {
    public static void main(String[] args)
    {
        // Create a new hashtable
        Dictionary<Integer, String>
            d = new Hashtable<Integer, String>();

        // Insert elements in the hashtable
        d.put(1, "Geeks");
        d.put(2, "for");
        d.put(3, "Geeks");

        // Print the Dictionary
        System.out.println("\nDictionary: " + d);

        // Display the removed value
        System.out.println(d.remove(3)
                           + " has been removed");

        // Print the Dictionary
        System.out.println("\nDictionary: " + d);
    }
}

输出:

Dictionary: {3=Geeks, 2=for, 1=Geeks}
Geeks has been removed

Dictionary: {2=for, 1=Geeks}

程序二:

// Java Program to illustrate
// java.util.Dictionary.remove() method

import java.util.*;

class GFG {
    public static void main(String[] args)
    {
        // Create a new hashtable
        Dictionary<String, String> d = new Hashtable<String, String>();

        // Insert elements in the hashtable
        d.put("a", "GFG");
        d.put("b", "gfg");

        // Print the Dictionary
        System.out.println("\nDictionary: " + d);

        // Display the removed value
        System.out.println(d.remove("a")
                           + " has been removed");
        System.out.println(d.remove("b")
                           + " has been removed");

        // Print the Dictionary
        System.out.println("\nDictionary: " + d);

        // returns true
        if (d.isEmpty()) {
            System.out.println("Dictionary "
                               + "is empty");
        }
        else
            System.out.println("Dictionary "
                               + "is not empty");
    }
}

输出:

Dictionary: {b=gfg, a=GFG}
GFG has been removed
gfg has been removed

Dictionary: {}
Dictionary is empty

参考:https://docs . Oracle . com/javase/7/docs/API/Java/util/dictionary . html # remove()

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