java treemap

TreeMap类HigherKey()方法 (TreeMap Class higherKey() method)

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

  HigherKey()方法在java.util包中可用。

• higherKey() method is used to return the lowest key value element higher than the given key element (key_ele).

  HigherKey()方法用于返回比给定键元素(key_ele)高的最低键值元素。

• higherKey() 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.

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

• higherKey() method may throw an exception at the time of returning an appropriate key element from this map.

  从该映射返回适当的键元素时， higherKey()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 Key higherKey(Key key_ele);

Parameter(s):

参数：

• Key key_ele – represents the key element to compare with.

  Key key_ele –表示要比较的关键元素。

Return value:

返回值：

The return type of the method is Key, it retrieves the lowest value key element that is higher than the given key element (key_ele) otherwise it returns null.

方法的返回类型为Key ，它检索比给定键元素(key_ele)高的最低值键元素，否则返回null。

Example:

例：

// Java program to demonstrate the example // of Key higherKey(Key key_ele) // method of TreeMap import java.util.*;public class HigherKeyOfTreeMap {
       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 higherKey(3) method is        // return the lowest key element         // higher than the given key element i.e. 4        // Display Returned Key Element        System.out.println("tm.higherKey(): " + tm.higherKey(3));    }}

Output

输出量

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

翻译自:

java treemap