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Java Collection, ArrayList Exercises: Join two array lists

Java Collection, ArrayList Exercises: Exercise-15 with Solution

Write a Java program to join two array lists.

Pictorial Presentation:

Java Collection, ArrayList Exercises: Join two array lists

Sample Solution:-

Java Code:

import java.util.ArrayList;
import java.util.Collections;
  public class Exercise15 {
  public static void main(String[] args) {
   ArrayList<String> c1= new ArrayList<String>();
          c1.add("Red");
          c1.add("Green");
          c1.add("Black");
          c1.add("White");
          c1.add("Pink");
          System.out.println("List of first array: " + c1);
          ArrayList<String> c2= new ArrayList<String>();
          c2.add("Red");
          c2.add("Green");
          c2.add("Black");
          c2.add("Pink");
          System.out.println("List of second array: " + c2);
         
      // Let join above two list
        ArrayList<String> a = new ArrayList<String>();
        a.addAll(c1);
        a.addAll(c2);
        System.out.println("New array: " + a);
        

     }
}

Sample Output:

List of first array: [Red, Green, Black, White, Pink]                  
List of second array: [Red, Green, Black, Pink]                        
New array: [Red, Green, Black, White, Pink, Red, Green, Black, Pink]

Flowchart:

Flowchart: Join two array lists.

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