Consider the following program which covers both constructors & overloaded methods:
Class Program:
Class MyProgram:
Consider the following detailed illustration to understand how the program works & how the output is obtained.
Firstly, each object is a distinct copy of the class. So, to show how the instance variables values of each object change over the sequence of main instructions, we are representing each objects by a rectangle for simplification and illustration.
Note that instructions in class MyProgram are numbered from 1 to 16, these numbers are written to be used in illustration.
Instruction 1 creates object P1 from class Program using the default constructor (the 1st constructor) as the parameter list indicates.
Effects on objects:
Effects on output: (Nothing)
Instruction 2 creates object P2 from class Program using the 2nd constructor as the parameter list indicates.
Effects on objects:
Effects on output: (Nothing)
Instruction 3 creates object P3 from class Program using the 3rd constructor as the parameter list indicates.
Effects on objects:
Effects on output: (Nothing)
Instruction 4 prints the values of x and y in object P1.
Note that the instruction uses the dot operator to reach the instance variables of object P1 because they are declared as public.
Effects on objects:(Nothing)
Effects on output:
Instruction 5 prints the values of x and y in object P2.
Note that the instruction uses the dot operator to reach the instance variables of object P2 because they are declared as public.
Effects on objects:(Nothing)
Effects on output:
Instruction 6 prints the values of x and y in object P3.
Note that the instruction uses the dot operator to reach the instance variables of object P3 because they are declared as public.
Effects on objects:(Nothing)
Effects on output:
Instruction 7 creates a new line at the output screen.
Effects on objects:(Nothing)
Effects on output:
Instruction 8 prints the values of x and y in object P1. Note that the compiler will choose the 1st print method in class Program
Effects on objects:(Nothing)
Effects on output:
Instruction 9 prints the values of x and y in object P2. Note that the compiler will choose the 2nd print method in class Program which adds the passed value to the value of x before printing to the output screen.
Effects on objects:
Effects on output:
Instruction 10 prints the values of x and y in object P2. Note that the compiler will choose the 2nd print method in class Program which adds the passed value to the value of x before printing to the output screen.
Effects on objects:
Effects on output:
Instruction 11 prints the values of x and y in object P3. Note that the compiler will choose the 3rd print method in class Program which adds the passed values to both the value of x and the value of y before printing to the output screen.
Effects on objects:
Effects on output:
Instruction 12 prints the values of x and y in object P3. Note that the compiler will choose the 3rd print method in class Program which adds the passed values to both the value of x and the value of y before printing to the output screen.
Effects on objects:
Effects on output:
Instruction 13 creates a new line at the output screen.
Effects on objects:(Nothing)
Effects on output:
Instruction 14 prints the values of x and y in object P1.
Note that the instruction uses the dot operator to reach the instance variables of object P1 because they are declared as public.
Effects on objects:(Nothing)
Effects on output:
Instruction 15 prints the values of x and y in object P2.
Note that the instruction uses the dot operator to reach the instance variables of object P2 because they are declared as public.
Effects on objects:(Nothing)
Effects on output:
Instruction 16 prints the values of x and y in object P3.
Note that the instruction uses the dot operator to reach the instance variables of object P3 because they are declared as public.
Effects on objects:(Nothing)
Effects on output:
Now, the main method terminates, so this is the output of the program:
To write the program using Eclipse, you should create a java project, then 2 .class files (To see how a project and a .class file are created, you can see Preparing Your Computer For Java Programming).
You need 2 .class files because each class is to be written in a separated file but inside the same project.
When you create a .class file you should consider that the name of the .class file is the same as the name of class to be written inside the file.
If you want a soft copy of the program please download it from Constructors & Overloaded Methods. So you can copy & paste the code in Eclipse.
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