Java TreeMap clone()方法及实例

在Java中，TreeMap类的clone()方法是用来返回所提到的树状图的浅层拷贝的。它只是创建一个地图的副本。

--> java.util Package
    --> TreeMap Class
        --> clone() Method 

语法

Tree_Map.clone()

参数： 该方法不接受任何参数。

返回类型： TreeMap的一个副本。

例1： 将字符串值映射到整数键上

// Java Program to Illustrate clone() method
// of TreeMap class
 
// Importing required classes
import java.util.*;
 
// Main class
public class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Creating an empty TreeMap by
        // declaring object of integer-string pairs
        TreeMap<Integer, String> tree_map
            = new TreeMap<Integer, String>();
 
        // Mapping string values to int keys
        // using put() method
        tree_map.put(10, "Geeks");
        tree_map.put(15, "4");
        tree_map.put(20, "Geeks");
        tree_map.put(25, "Welcomes");
        tree_map.put(30, "You");
 
        // printing all elements of TreeMap
        System.out.println("Initial Mappings are: "
                           + tree_map);
 
        // Displaying the cloned TreeMap
        // using clone()
        System.out.println("The cloned map look like this: "
                           + tree_map.clone());
    }
}

输出

Initial Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
The cloned map look like this: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}

例2： 将整数值映射到字符串键上

// Java Program  to Illustrate clone() Method
// of TreeMap class
 
// Importing required classes
import java.util.*;
 
// Main class
public class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Creating an empty TreeMap
        TreeMap<String, Integer> tree_map
            = new TreeMap<String, Integer>();
 
        // Mapping int values to string keys
        // using put() method
        tree_map.put("Geeks", 10);
        tree_map.put("4", 15);
        tree_map.put("Geeks", 20);
        tree_map.put("Welcomes", 25);
        tree_map.put("You", 30);
 
        // Displaying all elements initial mapping TreeMap
        System.out.println("Initial Mappings are: "
                           + tree_map);
 
        // Displaying the cloned TreeMap
        // using clone()
        System.out.println("The cloned map look like this: "
                           + tree_map.clone());
    }
}

输出

Initial Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}
The cloned map look like this: {4=15, Geeks=20, Welcomes=25, You=30}

注意： 同样的操作也可以通过不同数据类型的变化和组合对任何类型的映射进行操作。