java treemap

TreeMap類(lèi)pollFirstEntry()方法 (TreeMap Class pollFirstEntry() method)

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

  pollFirstEntry()方法在java.util包中可用。

• pollFirstEntry() method is used to return and then remove the entry (key-value pair) linked with the lowest key element value that exists in this TreeMap.

  pollFirstEntry()方法用于返回，然后刪除與此TreeMap中存在的最低鍵元素值鏈接的條目(鍵值對(duì))。

• pollFirstEntry() 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.

  pollFirstEntry()方法是一種非靜態(tài)方法，只能通過(guò)類(lèi)對(duì)象訪(fǎng)問(wèn)，如果嘗試使用類(lèi)名訪(fǎng)問(wèn)該方法，則會(huì)收到錯(cuò)誤消息。

• pollFirstEntry() method does not throw an exception at the time of returning first entry.

  返回第一個(gè)條目時(shí)， pollFirstEntry()方法不會(huì)引發(fā)異常。

Syntax:

句法：

public Map.Entry pollFirstEntry();

Parameter(s):

參數(shù)：

• It does not accept any parameter.

  它不接受任何參數(shù)。

Return value:

返回值：

The return type of the method is Map.Entry, it retrieves an entry with the lowest key element value when exists otherwise it returns null.

該方法的返回類(lèi)型為Map.Entry ，如果存在，則檢索具有最低鍵元素值的條目，否則返回null。

Example:

例：

// Java program to demonstrate the example // of Map.Entry pollFirstEntry () // method of TreeMap import java.util.*;public class PollFirstEntryOfTreeMap {public static void main(String[] args) {// Instantiates TreeMapTreeMap < Integer, String > tm = new TreeMap < Integer, String > ();// By using put() method is// to put the key-value pairs in// treemap tmtm.put(1, "C");tm.put(4, "C++");tm.put(3, "Java");tm.put(2, "Php");// Display TreeMap tmSystem.out.println("tm: " + tm);// By using pollFirstEntry() method is to// return and remove the key-value pairs// linked with the least key element value// i.e. "1"tm.pollFirstEntry();// Display updated TreeMap tmSystem.out.println("tm.pollFirstEntry(): " + tm);} }

Output

輸出量

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

翻譯自: https://www.includehelp.com/java/treemap-pollfirstentry-method-with-example.aspx

java treemap

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