CH2 – Declaring Variables And Assignment

In this exercise you do not create an actual Java program. Instead you use DrJava’s Interactions¬†Pane. The Interactions Pane allows you to type Java statements and quickly see the results without writing a complete program.

  1. Open DrJava and expand the Interactions Pane.


    DrJava Interactions Pane.

  2. Type the following lines.
> String message;
> int x;
> String firstName;
> String lastName;
> int hour, minute;
  1. Now type the following assignment statements.
> message = "hello";
> hour = 11;
> minute = 59;
> firstName = "James";
> lastName = "Brannan";
  1. Type the following to see the results of the assignment.
> message
> hour + ":" + minute
> firstName
> lastName
  1. Type the following line and review the result. Note that all three lines should be on the same line when printing multiple statements in the DrJava Interactions Pane.
> System.out.print(hour); System.out.print(":"); System.out.println(minute);

It is important to remember that this is DrJava’s Interaction pane. This pane is designed for learning Java statements. You are executing isolated statements and reviewing the result. You are not writing a complete Java program. For more information on the Interactions Pane, refer to DrJava’s online help page.

For more experience declaring and assigning variables, watch this video by LearningLad.