Examination #1 Review

Basic programming concepts

• Program, source code, byte code, compiler and interpreter
• Binary and hex numbers 
• Process of creating, editing , compiling and running a Java program 

Java basic program structure and output

• Java program structure ( write a complete Java program structure) 
• Using System.out.println or print to display an output 
• Display the Unicode characters 
• Escape sequences \n, \\, \”

Variables, data types, arithmetic expressions and output format

• Naming variables 
• Data types 
• Java arithmetic operator and expressions 
• Arithmetic operator order precedence 
• Cast
• Use JOptionPane.showInputDialog for input 
• Divide by integer and/or real numbers 
• Output format 
• Invoke class methods (Math.pow and Math.sqrt)

Classes, objects and methods

• Create an object
• Class World
  Constructor:  new World( ) or new World(world object)

• Turtle object methods
      turnRight()
      turnLeft()
      turn(int angle)
      forward(int numbeofsteps)
      moveTo(int x, int y)
      penDown()
      penUp()
      show()
      hide()
• Define an object method in the class
• Invoke an object method

Arrays

• Declare a one-dimensional array
• Create a one-dimensional array
• Declare and initialize a one-dimensional array
• Input a one-dimensional array
• Output a one-dimensional array
• Process a one-dimensional array

Picture objects

• Color representations
• Color class
  import java.awt.Color;
  Color constructor
  Color  colorObj = new Color (red value, green value, blue value);
  where red, green and blue values are ranged from 0 to 255
• Color object methods
  darker(), brighter()
• FileChooser.pickAFile();
• Creating a Picture object
  Picture  picObj = new Picture(filename)
  where filename is a string object
• Picture object methods
        show()
        Explore()
	getHeight()
        getWidth()
	getPixels()
	getPixel(int x, int y)
	WritePictureTo(String filename)

• Pixel object methods
	getX() and getY()
	getRed(), getGreen() and getBlue()
	setRed(int value), setGreen(int value) and setBlue(int value)
	getColor() return a Color object
	setColor(Color object)

Loops

1.	while loop

	while(condition)
	{ loop body
	}
2.	Counter-controlled loop
	Ex Display “Hello” 100 times
	int i =1;
	while(i<=100)
	{	System.out.println(“Hello”);
	i=i+1;
        }
	Ex
	int i =0;
	while(i<10);
	{ System.out.println(“Hello”);
	i=i+1;
        }

        Output: Nothing outputs.  A semicolon after the while loop makes an empty loop body.
c.	Ex
	int i=0;
	while(i<10)
		System.out.println(“Hello”);
		i=i+1;
        Output:  Hello displays continuously because there is no brace to include the statement i = i + 1;

        Correct solution:
                  int i=0;
	          while(i<10)
		 { System.out.println(“Hello”);
		 i=i+1;
                 }

3.	for loop
	Ex   Display “Hello” 100 times using for loop

        for(int i=0 ; i<100 ; i=i+1 )
	        System.out.println(“Hello”);
         Or
        for(int i=0; i<100; )
        { System.out.println(“Hello”);
	  i=i+1;
        }

	Ex   Use a for loop to display even numbers starting from 2 to 100
              for(int i=2; i<=100; i=i+2)
	          System.out.println(i);

	Ex Use a while loop to accumulate all the numbers starting from 2 to 200; display value
        int sum=0; //accumulated variable
        int i=2;
        while(i<=200)
        {sum=sum+i;
	 i=i+1;
        }
        System.out.println(sum);

Code Analyzing
i=2
i<=200  true
sum=0+2=2
i=3
i<=200 true
sum=2+3=5
i=4….

4.	for…each loop (Text Book  on page 93)
	Use only for objects
	Ex  Use for each loop to display the red values of all pixels in the picture whose filename is happy.gif

	int redvalue;	
	Picture picObj= new Picture(“c:/happy.gif”);
	Pixel[] pixArray = picObj.getPixels();
	for(Pixel pixObj:pixelArray)
         {redvalue=pixObj.getRed();
	  System.out.println(redvalue);                  
        }

5. Relational operators: < , <=, >=, == and !=

5.	Single-alternative decision statement
        if (condition)
        {  true body
        }

        dual-alternative decision statement
        if (condition)
        {  true body
        }
        else
        {
             false body
        }