A Simple Java Example

In this simple information system, the user inputs a student’s information to the program in 
different steps. After the information is complete, the system will display this information 
all together.
1) We need a class to store the student’s information; so we define a new class in our 
project and write the following fields into it.

public class Student {
	private String givenName;
	private String familyName;
	private long studentNo;
	private long birthyear; 
	
           public Student(String first, String family,long ID, long birthyear) {
		givenName=first;
		familyName=family;
		studentNo=ID;                         // The first constructor
		this.birthyear=birthyear;
	}

	
          public Student()
	{                                                       // The second constructor
	}
	

	public long calculate_age(int current_year){
		return (current_year-birthyear);
	}
	
	public String make_description()
	{
		return ("Given name: " + givenName + "\n"+ "Family name: " 
                     + familyName + "\n" +"ID number:" + studentNo + "\n" +   
                     "Year of birth: " + birthyear + "\n" );
	}
}
 
2) Also we need a class for displaying the student information. So we create another 
class in the project and write the followings:



import javax.swing.JOptionPane;  

public class DisplayInfo {
		public static int myear=2007;
		public static void main(String[] args) {
			String name,lname;
			long stdno,stdbirthyear;

			name =JOptionPane.showInputDialog( "Enter the student 
                                           first name" );
			lname =JOptionPane.showInputDialog( "Enter the 
                                           student last name" );          // Input the information
			String stdnotemp=JOptionPane.showInputDialog( "Enter 
                                           the student number" );
			String stdbirthyeartemp=JOptionPane.showInputDialog( 
                                           "Enter the student birth year" );
			
                                    stdno=Integer.parseInt(stdnotemp);
			stdbirthyear=Integer.parseInt(stdbirthyeartemp);   
			
                                    Student s;
			s=new Student(name,lname,stdno,stdbirthyear);
		          
                               JOptionPane.showMessageDialog( null, "The student 
                               information is"+ "\n" s.make_description()+ 
                                "age="+s.calculate_age(myear),"", // Output the information
                                JOptionPane.PLAIN_MESSAGE );

			}
		}




 1) Create the workspace and project

    a) File -> New -> Project -> Java Project
    b) Specify the Project Name
    c) Press finish

 2) Add a Class to the project

    a) Press right click on the project name
    b) New -> Class
    c) Specify the class name
  
3) Run the program
  
  a) Run -> Run as -> SWT Application 
 
4) Debug a program 
   
    a) Run-> Debug
    b) Set Breakpoint(s): Right Click on the left side of the desired line(s).
    c) Use Step Info and Step Over for controlling the running sequence
    d) Use Terminate button for finishing the debug mode