“Hello, World” and friends.

exercise No. 1

Extending class HelloWorld

Q:

  1. Fire up you IntelliJ Idea development environment and create the following class HelloWorld : 

    public class HelloWorld {

   public static void main(String[] args) {
      System.out.println("Hello, World ...");
   }
}

  2. Run the class and observe the output.

    As we will see later you actually run (or execute) the classes main(...) method rather than the class itself. Actually a class in Java™ cannot be run or executed.

  3. Extend your current code for producing multiple output lines: 

    Those who can do.
Those, who cannot, teach.
Those, who cannot teach, lecture trainee teachers teaching methodology.

A:

There are several options for creating a whole paragraph spanning multiple text lines:

  1. Using Java 13 multiline string literals (easy): 

    public static void main( String[] args ) {
  System.out.println("""
    Those who can do.
    Those, who cannot, teach.
    Those, who cannot teach, lecture trainee teachers teaching methodology.""" );
}

  2. Straightforward: Using multiple print statements: 

    public class HelloWorld {

 public static void main(String[] args) {
    System.out.println("Those who can do.");
    System.out.println("Those, who cannot, teach.");
    System.out.println(
      "Those who cannot teach lecture trainee teachers teaching methodology.");
   }
}

  3. Long strings exceeding your editor's desired maximum line length may be decomposed into smaller chunks using the “+” ❶ string concatenation operator: 

    public static void main(String[] args) {
  System.out.println(
    "Those who can do.\n"  + ❶
    "Those, who cannot, teach.\n"  +
    "Those, who cannot teach, " +
    "lecture trainee teachers teaching methodology."); // No \n at end, println(...) does it.
}

    Note

    »\n« represents the newline character. Without it the three sentences would be concatenated into a single long line.

    The System.out.println(...) method adds a final line break to the content in question.

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