Introduction to Java & BlueJ Environment

Q. Why is Java often termed as a platform?

Ans: Platform is the environment in which programs execute. Instead of interacting with the Operating System directly, Java programs runs on a virtual machine provided by Java, therefore Java is often referred to as a platform also.

Q. What is a bytecode?

Ans: Bytecode is a set of pseudo mechanic language instructions that are understood by the JVM (Java Virtual Machine) and are independent of the underlying hardware.

Q. What do you understand by JVM?

Ans: JVM or Java Virtual Machine is an abstract machine designed to be implemented on top of existing processors. It hides the underlying OS from Java application. Programs written in Java are compiled into Java byte-code, which is then interpreted by a special java Interpreter for a specific platform. Actually this Java interpreter is known as Java Virtual Machine (JVM).

Q. What is JDK (Java Development Kit)?

Ans: The Java development kit comes with a collection of tools that are used for developing and running java programs.

Q. What are Java APIs?

Ans: The Java APIs (Application Program Interface) consist of libraries of pre-compiled code that programmers can use in their application.

Q. Write the five characteristics of Java/BlueJ?

Ans: 1. Write Once Run Anywhere 2. Light weight code 3. Security 4. Built in Graphics 5. Object Oriented Language 6. Support Multimedia 7. Platform Independent. 8. Open Product.

Q. What do you know about BlueJ?

Ans: BlueJ is a Java development environment. It is an IDE (Integrated Development Environment), which includes an editor a debugger and a viewer.

Q. How you create, compile and execute a program in Java or BlueJ? Explain your answer?

Ans: Create: Click on new class button from BlueJ editor, then type the class name a program icon will be created. double click on it, a program editor will be open, erase the code and type your program coding. Compile: click the compile button on the left of the window or right click on the class icon and select compile from the menu options. Execute: Right click on the class icon and select new class name option. A dialogue box appears type the name of the object. A object icon will be created at the bottom. Right click on the object icon and select the method we want to execute.