treeset java_Java TreeSet add（）方法与示例

treeset java

TreeSet类的add()方法 (TreeSet Class add() method)

add() method is available in java.util package.
add()方法在java.util包中可用。
add() method is used to add the given object(ob) to this TreeSet when it does not already exist otherwise it ignores it.
add()方法用于将给定对象(ob)添加到此TreeSet中，如果该对象尚不存在，否则它将忽略它。
add() 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.
add()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。
add() method may throw an exception at the time of adding an object.
add()方法在添加对象时可能会引发异常。

ClassCastException: This exception may throw when the given parameter is incompatible.
ClassCastException ：如果给定参数不兼容，则可能引发此异常。

Syntax:

句法：

    public boolean add(Object ob);

Parameter(s):

参数：

Object ob – represents the object (ob) to be added in this TreeSet.
对象ob –表示要在此TreeSet中添加的对象(ob)。

Return value:

返回值：

The return type of the method is boolean, it returns true when the given object (ob) is to be added successfully otherwise it returns false when the given object is already exists in this TreeSet.

该方法的返回类型为boolean ，当成功添加给定对象(ob)时，它返回true；否则，当此TreeSet中已经存在给定对象时，它返回false。

Example:

例：

// Java program to demonstrate the example 
// of boolean add(Object ob) method of TreeSet 
import java.util.*;
public class AddOfTreeSet {
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 if not exists
tree_set.add("C");
tree_set.add("C++");
tree_set.add("JAVA");
tree_set.add("PHP");
tree_set.add("SFDC");
// Display TreeMap 
System.out.println("TreeSet: " + tree_set);
}
}

Output

输出量