java treemap

TreeMap类putAll()方法 (TreeMap Class putAll() method)

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

  putAll()方法在java.util包中可用。

• putAll() method is used to copy all the key-value pairs from the given map (m) and paste it into this map.

  putAll()方法用于复制给定映射(m)中的所有键值对，并将其粘贴到此映射中。

• putAll() 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.

  putAll()方法是一种非静态方法，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。

• putAll() method may throw an exception at the replacing mappings.

  putAll()方法可能会在替换映射处引发异常。

  • ClassCastException: This exception may throw when the given map (m) elements protect it from being saved in this Map.ClassCastException ：当给定的map(m)元素防止将其保存在此Map中时，可能会抛出此异常。
  • NullPointerException: This exception may throw when the given parameter is null exists.NullPointerException ：当给定参数为null时，可能引发此异常。

Syntax:

句法：

    public void putAll(Map m);

Parameter(s):

参数：

• Map m – represents the mappings to be saved in this TreeMap.

  映射m –表示要保存在此TreeMap中的映射。

Return value:

返回值：

The return type of the method is void, it returns nothing.

该方法的返回类型为void ，不返回任何内容。

Example:

例：

// Java program to demonstrate the example
// of void putAll(Map m) method of TreeMap
import java.util.*;
public class PutAllOfTreeMap {public static void main(String[] args) {// Instantiates two TreeMap
TreeMap < Integer, String > tm1 = new TreeMap < Integer, String > ();
TreeMap < Integer, String > tm2 = new TreeMap < Integer, String > ();
// By using put() method is
// to put the key-value pairs in
// treemap tm1
tm1.put(1, "C");
tm1.put(4, "C++");
tm1.put(3, "Java");
tm1.put(2, "Php");
// By using put() method is
// to put the key-value pairs in
// treemap tm2
tm2.put(1, "SQL");
tm2.put(2, "DBMS");
// Display TreeMap tm1
System.out.println("tm1: " + tm1);
// By using putAll() method is to
// put all the elements of tm2 in tm1
tm1.putAll(tm2);
// Display updated TreeMap tm1
System.out.println("tm1.putAll(tm2): " + tm1);
}
}

Output

输出量

tm1: {1=C, 2=Php, 3=Java, 4=C++}
tm1.putAll(tm2): {1=SQL, 2=DBMS, 3=Java, 4=C++}

翻译自: https://www.includehelp.com/java/treemap-putall-method-with-example.aspx

java treemap