Android Hello World

Watch out! This tutorial is over 2 years old. Please keep this in mind as some code snippets provided may no longer work or need modification to work on current systems.

Before you start writing your first example using Android SDK, you have to make sure that you have set-up your Android development environment properly. We also assume that you have a little bit working knowledge with Android Studio from class.

So let us proceed to write a simple Android Application which will print “Hello World!”.

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A “Hello, World” HTML document

Watch out! This tutorial is over 2 years old. Please keep this in mind as some code snippets provided may no longer work or need modification to work on current systems.

You create a file and put special character sequences called HTML elements into your file. These elements identify the structural parts of your document. When a Web browser displays the file, it will display your file’s content, but not the characters that make up the structure.

Here is an example:

Only the elements that you place in the BODY element (that is, between <BODY> and </BODY> ) ever get displayed in a Web browser’s window.

In this example, only the contents of the H1 element (between <H1> and </H1> ) and the P element (between <P> and </P> ) are displayed.

Hello World in C++

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This is how you would display “Hello World” in C++.

 

Hello World in C#

Watch out! This tutorial is over 2 years old. Please keep this in mind as some code snippets provided may no longer work or need modification to work on current systems.

This is how you would display “Hello World” in C#.

Hello World in Visual Basic .NET

Watch out! This tutorial is over 2 years old. Please keep this in mind as some code snippets provided may no longer work or need modification to work on current systems.

This is how you would display “Hello World” in Visual Basic.

The command line for compiling the program is the following:

In the previous line, /out specifies the output file, and /t indicates the target type.

Hello World in Java

Watch out! This tutorial is over 2 years old. Please keep this in mind as some code snippets provided may no longer work or need modification to work on current systems.

This is how you would display “Hello World” in your Java application.

We break the process of programming in Java into three steps:

  • Create the program by typing it into a text editor and saving it to a file named, say, HelloWorld.java.
  • Compile it by typing “javac HelloWorld.java” in the terminal window.
  • Execute (or run) it by typing “java HelloWorld” in the terminal window.

So, the code in our file would look like

To compile HelloWorld.java type the text below at the terminal

Once you compile your program, you can execute it. This is the exciting part, where the computer follows your instructions. To run the HelloWorld program, type the following in the terminal window:

That’s it!

Hello World in PowerShell

Watch out! This tutorial is over 2 years old. Please keep this in mind as some code snippets provided may no longer work or need modification to work on current systems.

This is how you would display “Hello World” in PowerShell.

Note: PowerShell commands also have the ability to be run in a script with the .ps1 extension but running scripts are disabled by default for security purposes. Firstly, you will need to set the Execution Policy. The cmdlet Get-ExecutionPolicy will show you that the initial policy is set to ‘Restricted’. This will prevent scripts from running. You can change it with the Set-ExecutionPolicy cmdlet. There are four options Restricted, Remote-signed, Signed and Unrestricted. We recommend Remote-Signed as it will allow you to run the scripts that you have created locally and still keep your machine secure.

So, just type

Now you can use notepad to create your first script. In Notepad type:

This will need to be saved in a file called something like HelloWorld.ps1.

Then from a PowerShell console type

The reason you need the .\ is because a PowerShell security feature ensures that you are targeting a specific script in a specific location,. And that’s all there is to it.

Hello World in Perl

Watch out! This tutorial is over 2 years old. Please keep this in mind as some code snippets provided may no longer work or need modification to work on current systems.

This is how you would display “Hello World” in Perl. It’s quite similar to Bash, but note the differences carefully!

Create a text file called hello_world.pl containing the following code:

Navigate to a directory where your hello_world.pl is located and make the file executable:
Now you are ready to execute your first perl script:

Hello World in Bash

Watch out! This tutorial is over 2 years old. Please keep this in mind as some code snippets provided may no longer work or need modification to work on current systems.

This is how you would display “Hello World” in Bash.

Create a text file called hello_world.sh containing the following code:

Navigate to a directory where your hello_world.sh is located and make the file executable:
Now you are ready to execute your first bash script: