Java Vector containsAll()
Java Vector类的
containsAll()方法用于检查正在使用的Vector 是否包含所有是否指定集合中的元素。如果此向量包含Collection中的所有元素，则返回true，否则返回false。
语法:
以下是
containsAll( )方法:
public boolean containsAll(Collection<?> c)
参数:
| 参数 |
说明 |
必需/可选 |
| c |
这是一个集合，其元素将被测试是否包含在使用的向量中。 |
必需 |
返回:
如果此向量包含指定集合中的所有元素，则
containsAll()方法将返回true。
异常:
NullPointerException -如果指定的集合为null，则此方法引发异常。
兼容性版本:
Java 1.2及更高版本
示例1:
import java.util.*;
public class VectorContainsAllExample1 {
public static void main(String arg[]) {
//Create an empty Vector
Vector<String> vc = new Vector<String>();
//Add values in the vector
vc.add("Facebook");
vc.add("Whatsapp");
vc.add("Twitter");
vc.add("Instagram");
//Create an empty list
List<String> list = new ArrayList<String>();
//Add values in the List
list.add("Facebook");
list.add("Whatsapp");
System.out.println("Does vector contains all list elements?: "+vc.containsAll(list));
list.add("Hindi100");
System.out.println("Does vector contains all list elements?: "+vc.containsAll(list));
}
}
输出:
Does vector contains all list elements?: true
Does vector contains all list elements?: false
示例2:
import java.util.Vector;
public class VectorContainsAllExample2 {
public static void main(String arg[]) {
//Create an empty Vector1
Vector<Integer> vector1 = new Vector<Integer>();
//Add element in vwctor1
vector1.add(11);
vector1.add(22);
vector1.add(33);
vector1.add(44);
//Create an empty Vector2
Vector<Integer> vector2 = new Vector<Integer>();
//Add element in vector2
vector2.add(22);
vector2.add(33);
//Check the existence of vector2 in the vector1
System.out.println("Existence: "+vector1.containsAll(vector2));
//Lets add a new element to vector2
vector2.add(101);
//Checking again
System.out.println("Existence: "+vector1.containsAll(vector2));
}
}
输出:
Existence: true
Existence: false
示例3:
import java.util.Vector;
public class VectorContainsAllExample3 {
public static void main(String arg[]) {
//Create an empty Vector1
Vector<Integer> vector1 = new Vector<Integer>(null);
//Create an empty Vector2
Vector<Integer> vector2 = new Vector<Integer>();
//Check the existence of vector2 in the vector1
System.out.println("Existence: "+vector1.containsAll(vector2));
}
}
输出:
Exception in thread "main" java.lang.NullPointerException
at java.base/java.util.Vector.<init>(Vector.java:178)
at myPackage.VectorContainsAllExample3.main(VectorContainsAllExample3.java:6)
