Implementing a Java Program :
Implementation of a Java program involves a series of steps. They include -
Creating the program :
We can create a program using any test editor. In this example, we will use Notepad. it is a simple editor included with the Windows Operating System. You can use a different text editor like NotePad++ etc. Let's open the Notepad & type the following Java code -
package myFirstJavaProject;
import java.util.Scanner;
public class myFirstJavaProgram {
public static void main(String args[]) {
// Variable Initialization
String strSuccess = "Bravo!! Now you are a Java programmer";
String strFailure = "Unfortunately You are not successfull right now, but trust me You will :)";
System.out.println("Let's understand Java program step by step");
System.out.println("So, are you ready for it? Please type Yes or No");
Scanner answer = new Scanner(System.in);
String input = answer.nextLine();
if (input.equals("Yes")) {
System.out.println(strSuccess);
} else {
System.out.println(strFailure);
}
}
}
Remember that, before we begin compiling the program, the Java Development Kit (JDK) must be properly installed on your system.
We must save this program in a file called "myFirstJavaProgram.java" ensuring that the file name contains the class name properly. This file is called the source file. Source file will always have the extension java. If a program contains multiple classes, the file name must be the class name of the class containing the main method.
![Compiling java program](/sites/default/files/inline-images/saving%20java%20program_0.png)
Compiling the program :
To compile the program, we must run the java compiler javac, with the name of the source file on the command line as shown below - javac myFirstJavaProgram.java If your program is error free then javac compiler creates a file called " myFirstJavaProgram.class" containing the bytecode of the program. Note that the compiler automatically names the bytecode file as <classname> .class.
a) Open the command prompt for the right path, where your executable java file is present.
![opening comment prompt for the right path](/sites/default/files/inline-images/opening%20comment%20prompt_0.png)
b) Type javac <yourJavaFileName.java> and press Enter as shown in below image. In this example, the java file name is "myFirstJavaProgram".
![Compiling java program](/sites/default/files/inline-images/compiling%20java%20program_1.png)
c) If your compilation is successful, if you look in your working folder, you can see that a file named myFirstJavaProgram.class has been created.
![java compilation compilation](/sites/default/files/inline-images/java%20compilation%20complilation_0.png)
Running the Program:
We need to use the Java interpreter to run a stand-alone program. At the command prompt, we have to type as follows - java myFirstJavaProgram Now interpreter will look for the main method in the program and begins execution from there. When executed, our program displays the following output -