在 Java 中从另一个数组中移除一个数组
为了在 java 中从另一个数组中移除一个数组，我们将使用 removeAll() 方法。如果我们从数组 2 中调用 remove all()函数并将数组 1 作为参数，这将从数组 2 中移除数组 1 的所有元素。
语法:
public boolean removeAll(Collection c)
参数:该方法将集合 c 作为包含要从该列表中移除的元素的参数。
返回值:如果该列表因调用而改变，则该方法返回真。
例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// 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);
}
}
Output
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]
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，我们需要重写 equals()和 hashCode()方法。
Java 语言(一种计算机语言，尤用于创建网站)
// 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);
}
}
}
Output
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)
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