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Java Collection, ArrayList Exercises: Insert an element into the array list at the first position

Java Collection, ArrayList Exercises: Exercise-3 with Solution

Write a Java program to insert an element into the array list at the first position.

Pictorial Presentation:

Java Collection, ArrayList Exercises: Insert an element into the array list at the first position

Sample Solution:-

Java Code:

import java.util.*;
  public class Exercise3 {
  public static void main(String[] args) {
  // Creae a list and add some colors to the list
  List<String> list_Strings = new ArrayList<String>();
  list_Strings.add("Red");
  list_Strings.add("Green");
  list_Strings.add("Orange");
  list_Strings.add("White");
  list_Strings.add("Black");
  // Print the list
  System.out.println(list_Strings);
  // Now insert a color at the first and last position of the list
  list_Strings.add(0, "Pink");
  list_Strings.add(5, "Yellow");
  // Print the list
  System.out.println(list_Strings);
 }
}

Sample Output:

Note: Exercise3.java uses unchecked or unsafe operations.              
Note: Recompile with -Xlint:unchecked for details.                     
[Red, Green, Orange, White, Black]                                     
[Pink, Red, Green, Orange, White, Yellow, Black]

Flowchart:

Flowchart: Insert an element into the array list at the first position.

Java Code Editor:

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Java: Tips of the Day

Try and catch:

Java is excellent at catching errors, but it can only recover gracefully if you tell it what to do. The cascading hierarchy of attempting to perform an action in Java starts with try, falls back to catch, and ends with finally. Should the try clause fail, then catch is invoked, and in the end, there's always finally to perform some sensible action regardless of the results. Here's an example:

try {
        cmd = parser.parse(opt, args); 
       
        if(cmd.hasOption("help")) {
                HelpFormatter helper = new HelpFormatter();
                helper.printHelp("Hello ", opt);
                System.exit(0);
                }
        else {
                if(cmd.hasOption("shell") || cmd.hasOption("s")) {
                String target = cmd.getOptionValue("tgt");
                } // else
        } // fi
} catch (ParseException err) {
        System.out.println(err);
        System.exit(1);
        } //catch
        finally {
                new Hello().helloWorld(opt);
        } //finally
} //try

It's a robust system that attempts to avoid irrecoverable errors or, at least, to provide you with the option to give useful feedback to the user. Use it often, and your users will thank you!

Ref: https://red.ht/3EZc9OC