java treemap

TreeMap類的firstEntry()方法 (TreeMap Class firstEntry() method)

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

  firstEntry()方法在java.util包中可用。

• firstEntry() method is used to retrieve the key-value pairs linked with the lowest value key element that exists in this TreeMap.

  firstEntry()方法用于檢索與此TreeMap中存在的最低值鍵元素鏈接的鍵值對。

• firstEntry() 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.

  firstEntry()方法是一個非靜態方法，只能通過類對象訪問，如果嘗試使用類名稱訪問該方法，則會收到錯誤消息。

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

  firstEntry()方法在返回條目時不會引發異常。

Syntax:

句法：

public Map.Entry firstEntry();

Parameter(s):

參數：

• It does not accept any parameter.

  它不接受任何參數。

Return value:

返回值：

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

該方法的返回類型為Map.Entry ，它檢索存在最低鍵元素的鍵值條目，否則當此TreeMap為“空白”時返回null。

Example:

例：

// Java program to demonstrate the example // of Map.Entry firstEntry() method of TreeMap import java.util.*;public class FirstEntryOfTreeMap {public static void main(String[] args) {// Instantiates a TreeMap objectTreeMap < Integer, String > tree_map = new TreeMap < Integer, String > ();// By using put() method is to add// key-value pairs in a TreeMaptree_map.put(10, "C");tree_map.put(20, "C++");tree_map.put(50, "JAVA");tree_map.put(40, "PHP");tree_map.put(30, "SFDC");// Display TreeMap System.out.println("TreeMap: " + tree_map);// By using firstEntry() method is to return// the first entry with the least key value// element exists in this TreeMapSystem.out.println("tree_map.firstEntry(): " + tree_map.firstEntry());} }

Output

輸出量

TreeMap: {10=C, 20=C++, 30=SFDC, 40=PHP, 50=JAVA} tree_map.firstEntry(): 10=C

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

java treemap

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