treeset java

TreeSet类的first()方法 (TreeSet Class first() method)

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

  first()方法在java.util包中可用。

• first() method is used to retrieve the first lowest element in this TreeSet.

  first()方法用于检索此TreeSet中的第一个最低元素。

• first() 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.

  first()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。

• first() method may throw an exception at the time of returning the first least object in this TreeSet.

  返回此TreeSet中的第一个最小对象时， first()方法可能会引发异常。

  NoSuchElementException – This exception may throw when this TreeSet is “blank”.

  NoSuchElementException-如果此TreeSet为“空白”，则可能引发此异常。

Syntax:

句法：

    public Element first();

Parameter(s):

参数：

• It does not accept any parameter.

  它不接受任何参数。

Return value:

返回值：

The return type of the method is Element, it gets the first least element exists in this TreeSet.

方法的返回类型为Element ，它获取此TreeSet中存在的第一个最小元素。

Example:

例：

// Java program to demonstrate the example 
// of Element first() method of TreeSet 
import java.util.*;
public class FirstOfTreeSet {
public static void main(String[] args) {
// Instantiates a TreeSet object
TreeSet < String > tree_set = new TreeSet < String > ();
// By using add() method is to add
// the given object of this TreeSet 
tree_set.add("C");
tree_set.add("C++");
tree_set.add("JAVA");
tree_set.add("PHP");
tree_set.add("SFDC");
// Display TreeSet
System.out.println("TreeSet: " + tree_set);
// By using first() method is to return
// the first least element exists in this TreeSet
Object first_least = tree_set.first();
// Display first_least
System.out.println("tree_set.first(): " + first_least);
}
}

Output

输出量

TreeSet: [C, C++, JAVA, PHP, SFDC]
tree_set.first(): C

翻译自: https://www.includehelp.com/java/treeset-first-method-with-example.aspx

treeset java