Java中的向量removeAll()方法

Java.util.vector.removeAll(Collection col)方法用于从向量中删除指定集合中存在的所有元素。

句法：

Vector.removeAll(Collection col)

参数：此方法接受一个强制参数col ，该参数是要从向量中删除其元素的集合。

返回值：如果向量由于操作而改变，则此方法返回true ，否则返回False 。

异常：如果指定的集合为空，该方法将抛出NullPointerException 。

下面的程序说明了Java.util.Vector.removeAll(Collection col) 方法：

方案一：

// Java code to illustrate removeAll()
import java.util.*;
  
public class VectorDemo {
    public static void main(String args[])
    {
  
        // Creating an empty Vector
        Vector vec_tor = new Vector();
  
        // Use add() method to add elements in the Vector
        vec_tor.add("Geeks");
        vec_tor.add("for");
        vec_tor.add("Geeks");
        vec_tor.add("10");
        vec_tor.add("20");
  
        // Output the Vector
        System.out.println("Vector: " + vec_tor);
  
        // Creating an empty Vector
        Vector colvec_tor = new Vector();
  
        // Use add() method to add elements in the Vector
        colvec_tor.add("Geeks");
        colvec_tor.add("for");
        colvec_tor.add("Geeks");
  
        // Remove the head using remove()
        boolean changed = vec_tor.removeAll(colvec_tor);
  
        // Print the result
        if (changed)
            System.out.println("Collection removed");
        else
            System.out.println("Collection not removed");
  
        // Print the final Vector
        System.out.println("Final Vector: " + vec_tor);
    }
}

输出：

Vector: [Geeks, for, Geeks, 10, 20]
Collection removed
Final Vector: [10, 20]

方案二：

// Java code to illustrate removeAll()
import java.util.*;
  
public class VectorDemo {
    public static void main(String args[])
    {
  
        // Creating an empty Vector
        Vector vec_tor = new Vector();
  
        // Use add() method to add elements in the Vector
        vec_tor.add(1);
        vec_tor.add(2);
        vec_tor.add(3);
        vec_tor.add(10);
        vec_tor.add(20);
  
        // Output the Vector
        System.out.println("Vector: " + vec_tor);
  
        // Creating an empty Vector
        Vector colvec_tor = new Vector();
  
        // Use add() method to add elements in the Vector
        colvec_tor.add(30);
        colvec_tor.add(40);
        colvec_tor.add(50);
  
        // Remove the head using remove()
        boolean changed = vec_tor.removeAll(colvec_tor);
  
        // Print the result
        if (changed)
            System.out.println("Collection removed");
        else
            System.out.println("Collection not removed");
  
        // Print the final Vector
        System.out.println("Final Vector: " + vec_tor);
    }
}

输出：

Vector: [1, 2, 3, 10, 20]
Collection not removed
Final Vector: [1, 2, 3, 10, 20]