Eliminar una array de otra array en Java

Para eliminar una array de otra array en Java, usaremos el método removeAll() . Esto eliminará todos los elementos de la array1 de la array2 si llamamos a la función removeAll() de la array2 y la array1 como parámetro.

Sintaxis:

public boolean removeAll(Collection c)

Parámetros: este método toma la colección c como un parámetro que contiene elementos que se eliminarán de esta lista.

Valor devuelto: este método devuelve verdadero si esta lista cambió como resultado de la llamada.

Ejemplo 1:

// 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<Integer> firstList = new ArrayList<>();
  
        // creating second array
        List<Integer> 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);
    }
}

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]

Ejemplo 2:

En este ejemplo, en lugar de usar clases contenedoras de Java, usaremos la clase definida por el usuario, pero para usar la clase definida por el usuario necesitamos anular los métodos equals() y hashCode().

// 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<friendsDetail> 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<friendsDetail> 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);
        }
    }
}

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)