Java program to remove element from an ArrayList of a specific index :
In this program, we will learn how to remove an element of a specific index from an ArrayList. First, we will take ‘n’ number of inputs from the user . Next we will get the index of the number to be removed. To remove an element from a ArrayList, we can use ‘remove(index)’ method. ‘index’ is the index number. If the index is available, we will remove that number , otherwise we will ask the user for a valid input.
Following algorithm we are going to use in this example :
Algorithm :
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Get the count of numbers from the user.
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Use one ‘for’ loop and read all numbers . Insert all in an arraylist.
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Print the arraylist.
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Ask the user , which index number need to be removed.
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Use one infinite loop. This loop will run till the arraylist becomes empty or if the user enters ‘-1’ as input.
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After the index is read, always check if it is valid or not. If valid, remove the number from the arraylist at that index.
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Repeat the while loop again.
Java Program :
import java.util.ArrayList;
import java.util.Scanner;
public class Main {
private static void print(String message) {
System.out.print(message);
}
private static void println(String message) {
System.out.println(message);
}
public static void main(String[] args) throws java.lang.Exception {
Scanner sc = new Scanner(System.in);
//initialize an arraylist
ArrayList numberList = new ArrayList();
println("How many numbers you want to add ?");
//read user input total count
int no = sc.nextInt();
int userInputNo;
//read all numbers from
for (int i = 0; i < no; i++) { print("Enter No " + (i + 1) + " : "); userInputNo = sc.nextInt(); numberList.add(userInputNo); } //print the arraylist println(""); println("You have entered : "); println(numberList.toString()); //ask the user which number want to remove while (true) { if (numberList.size() == 0) { println("Empty arraylist, Exiting..."); break; } println(""); println("Enter index no. you want to remove from this list , -1 to exit : "); int index = sc.nextInt(); if (index == -1) { println("Exiting..."); break; } else if (index >= numberList.size()) {
println("Please enter a valid index no.");
continue;
}
numberList.remove(index);
println("");
println("Arraylist after element on position " + index + " removed : ");
println(numberList.toString());
}
}
}
Sample Output :
How many numbers you want to add ?
3
Enter No 1 : 4
Enter No 2 : 5
Enter No 3 : 6
You have entered :
[4, 5, 6]
Enter index no. you want to remove from this list , -1 to exit :
1
Arraylist after element on position 1 removed :
[4, 6]
Enter index no. you want to remove from this list , -1 to exit :
0
Arraylist after element on position 0 removed :
[6]
Enter index no. you want to remove from this list , -1 to exit :
3
Please enter a valid index no.
Enter index no. you want to remove from this list , -1 to exit :
0
Arraylist after element on position 0 removed :
[]
Empty arraylist, Exiting...
Process finished with exit code 0