ECE325-Lab 1 Java Basics, Heap Sort and Eclipse Solved

These labs are generally intended to let you explore concepts introduced in the course lectures. During each lab, you need to follow the instructions from problem setup to deliverables.

This lab contains 3 deliverables, which you should demo to the lab instructor.

1.1  Eclipse
The Eclipse platform is a generic integrated development environment (IDE) foundation without any focus on a specific programming language. The platform contains IDE functionality and is built with components creating applications by using component subsets. Developers create, share and edit generic projects and files in the platform, while participating within a multiple team development environment repository. However, it is written mostly in Java and most of the time is used to develop applications in this programming language, but it covers other languages such as: C, C++, Ruby, R, JavaScript, PHP, Python ...

In this lab we will focus on Eclipse usage in writing, editing and running Java programs.

1.2  Java Requirements of Eclipse
Eclipse requires an installed Java runtime (at least Java 5). Java can be downloaded in two flavors, a JRE

(Java runtime environment) and a JDK (Java development tools) version. The Eclipse IDE contains its own Java compiler hence a JRE is sufficient for most tasks with Eclipse. The JDK version of Java is required if you compile Java source code on the command line and for advanced development scenarios, for example if you use automatic builds or if you develop Java web applications.

1.3  Eclipse Resources
           Resource                                         URL



Eclipse Homepage
http://www.eclipse.org/
Download Eclipse
http://www.eclipse.org/downloads/
Eclipse Online Tutorials
http://www.eclipse.org/resources/
2   Deliverable 1 -- Create and Run a Simple Java Program (Heap Sort)
Sort a list of integers using the heap sort algorithm:

•        http://www.youtube.com/watch?v=WYII2Oau_VY (Super short, no words, pictures only)

•        http://www.youtube.com/watch?v=B7hVxCmfPtM (The traditional version from M.I.T., very, very long)     Or find your own

Note: Write carefully, you are going to reuse this code later!

Step 1: Launch Eclipse

eclipse
Open the Eclipse IDE. It can be done at terminal by typing .

Step 2: Create a new project

Select File = New = Java Project = Name your project = Finish.

Step 3: Add a new class

public static void main
Select your project = File = New ⇒ Class = Name the class = check  

(String[] args) = Finish.

For this lab, just copy the source file HeapSort.java and paste into the src folder of the project.

Step 4: Implement your class

Finish the
sort
 method.
Step 5: Run you code
Run the code (Run as = Java application).

DEMO this deliverable to the lab instructor.

 

3   Deliverable 2 -- Add a Library to the Build Path
In this part, we want you to edit your source code and add a library to the build path.

3.1  Edit Your Code
An import statement is a way of making more of the functionality of Java available to your program. Java can do a lot of things, but you do not need all of them so often. It has its classes divided into packages.

Your own classes are part of packages, too. So, anything that isn't in the
java.lang
 package or the local
package needs to be imported.
Step 1: Import libraries

Add the two following imports to the beginning of your source code:

import components.simplewriter.SimpleWriter; import components.simplewriter.SimpleWriter1L;
Step 2: Rewrite the output code

Edit your print/println commands by instantiating an object of SimpleWriter. For example, substitute: System.out.println(array[c]);

with:

SimpleWriter out = new SimpleWriter1L(); out.println(array[c]); out.close();
Step 3: Run your code

Run your code and see there are some errors.

The reason for these errors is that the components in the import lines, SimpleWriter and SimpleWriter1L, are from the components.jar, but we have not told Eclipse to use it yet.

3.2  Add the Library to Your Project Build Path
Step 1: Download the library

Save the components.jar in your home directory (or home directory of your project).

Step 2: Configure the project

Right-click on your project = Build Path = Configure Build Path = Add External Jars= Select the library = Finish.

Errors should disappear and you would be able to run your code.

DEMO this deliverable to the lab instructor.

4   Deliverable 3 -- Run Your Java Code outside of Eclipse
Eclipse has implemented its own java compiler called Eclipse Compiler for Java (ECJ), which is based on IBM's Jikes java compiler. Thus, Eclipse is automatically compiling your code on-the-fly to create an instant view of the result. In this part, you need do thing manually.

4.1  Runable JAR
A runnable JAR is just like a EXE file in Windows, which means you can double click it to run. However, what your heap sort is doning is just outputting results into the console, so you still need the terminal/cmd/PowerShell to run it.

Select File = Export... = Java = Runnable JAR file ⇒ Next:

•        Launch configuration: select your HeapSort;

•        Export destination: type your target JAR file path and name;

•        Library handling: choose the last option Copy required libraries into a sub-folder next to the generated JAR.

Click Finish, and you are ready to go:

java −jar HeapSort.jar
4.2  Compile and Run by JDK
Step 1: Copy your source codes to home directory

cp src/HeapSort.java ~      # "~" refers to the home directory of your account cp components.jar ~
Note: your HeapSort.java must use the
SimpleWriter
 and
SimpleWriter1L
.

CLASSPATH
Step 2: Configure the 

JDK requires an important environmental variable CLASSPATH to compile and run codes. In Linux, you can do it as follows:

export CLASSPATH="your_class_paths"     # You need fill in the actual paths echo $CLASSPATH                         # Print your class paths In this lab, your have two groups of classes:


Your own classes, which in this case is your
HeapSort
;

The third party library classes, which is the components.jar.
CLASSPATH
The  must contain the paths of both groups. Try figure it out.

Step 3: Compile and run

javac HeapSort.java     # Now you can find the file HeapSort.class at your home directory java HeapSort           # Do not add the ".class" extension