java treemap

TreeMap类的get()方法 (TreeMap Class get() method)

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

  get()方法在java.util包中可用。

• get() method is used to retrieves the associated value element for the given key element (key_ele) when it exists otherwise it returns null.

  get()方法用于在给定键元素(key_ele)存在时检索其关联的value元素，否则返回null。

• get() 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.

  get()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。

• get() method may throw an exception at the time of returning associated key-value elements from this map.

  从此映射返回关联的键值元素时， get()方法可能会引发异常。

  • ClassCastException: This exception may throw when the given parameter is incompatible to compare with.ClassCastException ：当给定参数不兼容时，可能引发此异常。
  • NullPointerException: This exception may throw when the given element is null exists.NullPointerException ：当给定元素为null时，可能引发此异常。

Syntax:

句法：

public Value get(Object key_ele);

Parameter(s):

参数：

• Key key_ele – represents the key element whose mapped value is to be retrieved.

  Key key_ele –表示要检索其映射值的key元素。

Return value:

返回值：

The return type of the method is Value, it retrieves the value element associated for the given key element when exists otherwise it returns null.

该方法的返回类型为Value ，它在存在时检索与给定键元素关联的value元素，否则返回null。

Example:

例：

// Java program to demonstrate the example // of Value get(Object key_ele) // method of TreeMap import java.util.*;public class GetOfTreeMap {
       public static void main(String[] args) {
           // Instantiates TreeMap        TreeMap < Integer, String > tm = new TreeMap < Integer, String > ();        // By using put() method is        // to put the key-value pairs in        // treemap tm        tm.put(1, "C");        tm.put(4, "C++");        tm.put(3, "Java");        tm.put(2, "Php");        // Display TreeMap tm        System.out.println("tm: " + tm);        // By using get(4) method is used        // to return the value associated        // with the given key element "4"        // Display Returned Value Element        System.out.println("tm.get(4): " + tm.get(4));    }}

Output

输出量

tm: {1=C, 2=Php, 3=Java, 4=C++}tm.get(4): C++

翻译自:

java treemap