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    TreeMap类的java.util.TreeMap.get()方法用于检索或获取由参数中提到的特定键映射的值。当地图不包含密钥的这种映射时,它返回NULL。

    句法:

    Tree_Map.get(Object key_element

    参数:该方法采用对象类型的一个参数key_element,并引用应该获取其关联值的键。

    返回值:该方法返回与参数中的key_element关联的值。

    下面的程序说明了java.util.TreeMap.get() 方法的工作原理

    程序1:将字符串值映射到整数键。

    // Java code to illustrate the get() method
    import java.util.*;
      
    public class Tree_Map_Demo {
        public static void main(String[] args)
        {
      
            // Creating an empty TreeMap
            TreeMap<Integer, String> tree_map = new TreeMap<Integer, String>(); 
      
            // Mapping string values to int keys
            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");
      
            // Displaying the TreeMap
            System.out.println("Initial Mappings are: " + tree_map);
      
            // Getting the value of 25
            System.out.println("The Value is: " + tree_map.get(25));
      
            // Getting the value of 10
            System.out.println("The Value is: " + tree_map.get(10));
        }
    }
    

    输出:

    Initial Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
    The Value is: Welcomes
    The Value is: Geeks

    程序2:将整数值映射到字符串键。

    // Java code to illustrate the get() method
    import java.util.*;
     
    public class Tree_Map_Demo {
        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
            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 the TreeMap
            System.out.println("Initial Mappings are: " + tree_map);
     
            // Getting the value of "Geeks"
            System.out.println("The Value is: " + tree_map.get("Geeks"));
     
            // Getting the value of "You"
            System.out.println("The Value is: " + tree_map.get("You"));
        }
    }
    

    输出:

    Initial Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}
    The Value is: 20
    The Value is: 30

    注意:对于具有不同数据类型的变体和组合的任何类型的映射,都可以执行相同的操作。

     
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