Helps You Can See During the Loop and Decision Test

• Java class setup

public class MyClassName
{
     public static void main( )
     {
           // your statements here ending in semi-colon
     }
     public static int otherroutine(double x, String y)
     {
           // your statements here ending in semi-colon
     }
}

• print a line
  • System.out.println(<whatever you want to print> + <whatever you want to print> );

 

• Setup to read something from the screen:

• In Java: there are 2 commands needed:
  
• before the class starts, import the scanner class using: import java.util.Scanner;
• inside the method, create a scanner object using: Scanner kbd = new Scanner(System.in);

 

• Read something from the screen:
  • In Java: <your variable> = < name of the scanner you created above>.nextLine();
  • Use the scanner method that matches your variable type.
  • example to get the whole line: myStringVar = kbd.nextLine();
  • example to get the next word: myStringVar = kbd.next();
  • example to get the next double: mydoubleVar = kbd.nextDouble();
  • example to get the next int: myIntVar = kbd.nextInt();
  • See Sun's page on scanner for much more
    

• Create boolean expressions:
  • use comparison operator: ==, <,>,<=,>=,!=
  • use logical indicator -> OR is || AND is &&

   

• Creating methods:

  public static return_type method_name (type parm1, type parm2)
  {
  ...
  ...
  return expression;
  }

  Calling methods:

  object_or_class.method_name(parm1, parm2);

  ---

  If / if else / else

  if (condition that evaluates to true or false)
  {
  // do something
  }
  else if (condition that evaluates to true or false) // remember that everything that met first criteria doesn't get here
  {
  // do something else
  }
  .
  . // repeat else if as needed
  .
  else // remember to put no condition
  {
  // do something
  }

  ---

  Loops

  For loop - repeats when you know the number of times to repeat

  
  for (statement to start the loop; condition that evaluates to true or false; statement to run when the loop repeats)
  {
  // do something
  }

  While loop - repeats until some condition is met

  
  while (condition that evaluates to true or false)
  {
  // do something
  // at some point, set the condition to stop
  }

• Math
  • absolute value: Math.abs(#)
  • random: Math.random()
  • minimum: Math.min(#,#)
  • maximum: Math.max(#,#)
  • raise to a power: Math.max(x,y) : Note: x is raised to y.
    

• Strings
  • stringvar.charAt(3) // will return a character
  • stringvar.length() // will return an integer
  • stringvar.toUpperCase() // will return a String that is all uppercase
  • stringvar.toLowerCase() // will return a String that is all lowercase
  • stringvar.subString(2) // will return a String starting in position 2 to the end
  • stringvar.subString(2, 5) // will return a String starting in position 2 and ending in position 4
  • stringvar.equals(somethingOtherString) // will return either true or false (a boolean)

(See your Java Tools)