在Java中从另一个数组中删除一个数组

为了从Java中的另一个数组中删除一个数组，我们将使用removeAll()方法。如果我们从 array2 和 array1 中调用 removeAll()函数作为参数，这将从 array2 中删除 array1 的所有元素。

句法：

public boolean removeAll(Collection c)

参数：此方法将集合 c 作为包含要从此列表中删除的元素的参数。

返回值：如果此列表因调用而更改，则此方法返回 true。

示例 1：

Java

// Java program to Remove One Array From Another Array
  
import java.util.ArrayList;
import java.util.List;
  
class GFG {
    public static void main(String[] args)
    {
  
        // creating first array
        List firstList = new ArrayList<>();
  
        // creating second array
        List secondList = new ArrayList<>();
  
        // adding elements in first array
        firstList.add(100);
        firstList.add(200);
        firstList.add(300);
        firstList.add(400);
        firstList.add(500);
        firstList.add(600);
  
        // adding elements in second array
        secondList.add(300);
        secondList.add(500);
        
        // displaying element of first array
        System.out.println("elements in first array "
                           + firstList);
        
        // displaying element of second array
        System.out.println("elements in second array "
                           + secondList);
        
        // removing elements from firstarray
        firstList.removeAll(secondList);
  
        // displaying elements of first array
        // after removing elements of second array
        // from first array
        System.out.println("first array after removing second array from first array\n"
            + firstList);
    }
}

输出

elements in first array [100, 200, 300, 400, 500, 600]
elements in second array [300, 500]
first array after removing second array from first array
[100, 200, 400, 600]

示例 2：

在这个例子中，我们将使用用户定义的类，而不是使用Java的包装类，但是为了使用用户定义的类，我们需要覆盖 equals() 和 hashCode() 方法。

Java

// Java program to Remove One Array From Another Array
  
import java.io.*;
import java.util.*;
  
class friendsDetail {
  
    // class field
    private String name;
    private String nickName;
  
    // parameterised constructor
    public friendsDetail(String name, String nickName)
    {
        this.name = name;
        this.nickName = nickName;
    }
  
    // getter for name
    public String getName() { return name; }
  
    // setter for name
    public void setName(String name) { this.name = name; }
  
    // getter for nickname
    public String getnickName() { return nickName; }
  
    // setter for nickname
    public void setNickName(int id)
    {
        this.nickName = nickName;
    }
  
    @Override public boolean equals(Object o)
    {
  
        if (this == o)
            return true;
  
        if (!(o instanceof friendsDetail))
            return false;
  
        friendsDetail that = (friendsDetail)o;
  
        return Objects.equals(getName(), that.getName())
            && Objects.equals(nickName, that.nickName);
    }
  
    @Override public int hashCode()
    {
        return Objects.hash(getName(), nickName);
    }
  
    // overriding toString method
    public String toString()
    {
        // return super.toString();
        return "(" + this.getName() + ":"
                        + this.getnickName() + ")";
    }
}
public class GFG {
    public static void main(String[] args)
    {
        ArrayList firstArrayList = new ArrayList<>();
  
        System.out.println("Our First ArrayList\n");
  
        // adding elements to first ArrayList
        firstArrayList.add(new friendsDetail("Amit", "Ghulla"));
        firstArrayList.add(new friendsDetail("Yashdeep", "Dopa"));
        firstArrayList.add(new friendsDetail("Jyoti", "Kauwa"));
        firstArrayList.add(new friendsDetail("Suraj", "Bhindi"));
        firstArrayList.add(new friendsDetail("Himanshu", "Lalten"));
        firstArrayList.add(new friendsDetail("Sarthak", "Nagin"));
        firstArrayList.add(new friendsDetail("Tsering", "Battak"));
        firstArrayList.add(new friendsDetail("Abhishek", "Liquid"));
  
        // Displaying output of first array using enhanced
        // for loop
        for (friendsDetail friend : firstArrayList) {
            System.out.println(friend);
        }
  
        ArrayList secondArrayList = new ArrayList<>();
  
        System.out.println("\nOur Second ArrayList\n");
        
        // adding elements to second ArrayList.
        secondArrayList.add(new friendsDetail("Amit", "Ghulla"));
        secondArrayList.add(new friendsDetail("Jyoti", "Kauwa"));
        secondArrayList.add(new friendsDetail("Himanshu", "Lalten"));
        secondArrayList.add(new friendsDetail("Abhishek", "Liquid"));
  
        // Displaying output of original array using
        // enhanced for loop
        for (friendsDetail friend : secondArrayList) {
            System.out.println(friend);
        }
  
        // removing second array elements from first array
        firstArrayList.removeAll(secondArrayList);
  
        System.out.println(
          "\nFirst array after removing second array from first array\n");
  
        // Displaying first array after removing second
        // array elements from first array
        for (friendsDetail friend : firstArrayList) {
            System.out.println(friend);
        }
    }
}

输出

Our First ArrayList

(Amit:Ghulla)
(Yashdeep:Dopa)
(Jyoti:Kauwa)
(Suraj:Bhindi)
(Himanshu:Lalten)
(Sarthak:Nagin)
(Tsering:Battak)
(Abhishek:Liquid)

Our Second ArrayList

(Amit:Ghulla)
(Jyoti:Kauwa)
(Himanshu:Lalten)
(Abhishek:Liquid)

First array after removing second array from first array

(Yashdeep:Dopa)
(Suraj:Bhindi)
(Sarthak:Nagin)
(Tsering:Battak)