hashmap clone

HashMap类clone()方法 (HashMap Class clone() method)

• clone() method is available in java.util package.

  clone()方法在java.util包中可用。

• clone() method is used to get a cloned copy of this HashMap instance or in other words, we can say it returns a shallow copy of this HashMap.

  clone()方法用于获取此HashMap实例的克隆副本，换句话说，可以说它返回此HashMap的浅表副本。

• clone() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  clone()方法是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• clone() method does not throw an exception at the time of cloning an object.

  clone()方法在克隆对象时不会引发异常。

Syntax:

句法：

    public Object clone();

Parameter(s):

参数：

• It does not accept any parameter.

  它不接受任何参数。

Return value:

返回值：

The return type of the method is Object, it clones this HashMap.

该方法的返回类型为Object ，它将克隆此HashMap。

Example:

例：

// Java program to demonstrate the example 
// of Object clone() method of HashMap 
import java.util.*;
public class CloneOfHashMap {
public static void main(String[] args) {
// Instantiates a HashMap object
HashMap < Integer, String > hm = new HashMap < Integer, String > ();
HashMap < Integer, String > clone_map = new HashMap < Integer, String > ();
// By using put() method is to add
// key-value pairs in a TreeMap
hm.put(10, "C");
hm.put(20, "C++");
hm.put(50, "JAVA");
hm.put(40, "PHP");
hm.put(30, "SFDC");
// Display HashMap and clone_map
System.out.println("HashMap: " + hm);
System.out.println("CloneMap: " + clone_map);
// By using clone() method is to clone
// this object
clone_map = (HashMap) hm.clone();
//Display clone_map
System.out.println("hm.clone(): " + clone_map);
}
}

Output

输出量

HashMap: {50=JAVA, 20=C++, 40=PHP, 10=C, 30=SFDC}
CloneMap: {}
hm.clone(): {40=PHP, 50=JAVA, 10=C, 20=C++, 30=SFDC}

翻译自: https://www.includehelp.com/java/hashmap-clone-method-with-example.aspx

hashmap clone