Java ArrayDeque removeAll()方法

ArrayDeque的 removeAll() 方法是用来移除ArrayDeque和作为参数传递的集合中的所有元素。该方法首先收集集合中的所有元素，然后开始从ArrayDeque中移除与集合中的元素相同的元素。在该方法执行后，该ArrayDequeu将不包含与集合相同的元素。如果这个ArrayDeque因调用此方法而发生变化，则此方法为True。

语法

public boolean removeAll(Collection<? extends E> col)

参数： 该方法需要一个参数c，代表我们想从这个deque中删除的元素集合。

返回： 如果这个deque因调用此方法而发生变化，则此方法返回True。

异常： 如果指定的集合或其任何元素为空，该方法将抛出NullPointerException。

下面的程序说明了ArrayDeque的removeAll()方法：

程序1： 演示ArrayDeque的removeAll()方法的程序，它将从一个包含数字的集合中删除与元素相同的元素。

// Java Program Demonstrate removeAll()
// method of ArrayDeque
  
import java.util.*;
public class GFG {
  
    public static void main(String[] args)
    {
  
        // create an ArrayDeque which going to
        // contains a list of Numbers
        ArrayDeque<Integer> Numbers = new ArrayDeque<Integer>();
  
        // Add Number to list
        Numbers.add(23);
        Numbers.add(32);
        Numbers.add(45);
        Numbers.add(63);
  
        // print ArrayDeque before calling removeAll()
        System.out.println("Before calling removeAll()");
        print(Numbers);
  
        // create a collection of Number to
        // remove elements from ArrayDeque using removeAll()
        ArrayList<Integer> col = new ArrayList<Integer>();
  
        // add Numbers to collection
        col.add(45);
        col.add(44);
        col.add(63);
  
        // remove Numbers same as elements of collection
        // from ArrayDeque using removeAll()
        Numbers.removeAll(col);
  
        // print ArrayDeque after calling removeAll()
        System.out.println("After calling removeAll()");
        print(Numbers);
    }
  
    // printing all elements of ArrayDeque
    public static void print(ArrayDeque<Integer> arDe)
    {
  
        arDe.forEach((n) -> System.out.print(n + " "));
  
        System.out.println();
    }
}

输出。

Before calling removeAll()
23 32 45 63 
After calling removeAll()
23 32

程序2： 演示ArrayDeque的removeAll()方法的程序，该方法将从学生姓名集合中删除相同的元素。

// Java Program Demonstrate removeAll()
// method of ArrayDeque
  
import java.util.*;
public class GFG {
  
    public static void main(String[] args)
    {
  
        // create an ArrayDeque which going to
        // contains a list of Student names which is actually
        // string values
        ArrayDeque<String> students = new ArrayDeque<String>();
  
        // Add Strings to list
        // each string represents student name
        students.add("Ram");
        students.add("Mohan");
        students.add("Sohan");
        students.add("Rabi");
  
        // print ArrayDeque before calling removeAll()
        System.out.println("Before calling removeAll()");
        print(students);
  
        // create a collection of Number to
        // remove elements from ArrayDeque using removeAll()
        LinkedList<String> col = new LinkedList<String>();
  
        // add Names in collection
        col.add("Rabi");
        col.add("Sohan");
  
        // remove the elements same as collection
        // from ArrayDeque using removeAll()
        students.removeAll(col);
  
        // print ArrayDeque
        System.out.println("After calling removeAll()");
        print(students);
    }
  
    // printing all elements of ArrayDeque
    public static void print(ArrayDeque<String> arDe)
    {
  
        System.out.println("List of Students Name:");
  
        arDe.forEach((n) -> System.out.print(" | " + n + " | "));
  
        System.out.println("\n");
    }
}

输出。

Before calling removeAll()
List of Students Name:
 | Ram |  | Mohan |  | Sohan |  | Rabi | 

After calling removeAll()
List of Students Name:
 | Ram |  | Mohan |

程序3： 演示由removeAll()方法引发的异常的程序。

// Java Program Demonstrate Exception thrown by removeAll()
// method of ArrayDeque
  
import java.util.*;
public class GFG {
  
    public static void main(String[] args)
    {
  
        // create an ArrayDeque which going to
        // contains a list of Numbers
        ArrayDeque<Integer> Numbers = new ArrayDeque<Integer>();
  
        // Add Number to list
        Numbers.add(223);
        Numbers.add(132);
        Numbers.add(345);
        Numbers.add(563);
  
        // create a collection of Number which is null
        ArrayList<Integer> col = null;
  
        try {
            // call removeAll() method
            Numbers.removeAll(col);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出。