Chapter 03 Summary

Methods with parameters

Creating methods:

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

Calling methods:

object_or_class.method_name(parm1, parm2);

You need the class or object if the method is not in your own class. Then, you need the object if the method needs to know some information that is not passed in.

Math

• abs
• random
• knows PI and E

Creating and using objects like Point

• Create with: ClassName objName = new ClassName(parms) ex: Point x = new Point(5,2);
• Use with: objName.method(parms) ex: objName.setLocation(3,5);

Strings

• stringvar.charAt(3) // will be a character
• stringvar.length() // will be an integer
• stringvar.toUpperCase() // will be a String that is all uppercase
• stringvar.toLowerCase() // will be a String that is all lowercase
• stringvar.subString(2) // will be a String starting in position 2 to the end
• stringvar.subString(2, 5) // will be a String starting in position 2 and ending in position 4
• stringvar.equals(somethingOtherString) // will be either true or false (a boolean) (did not use)

ex: newString = myOriginalString.toLowerCase();

Also, strings can be put together into another string with the +

ex: newString = string1 + string2;

Scanner object knows: How toread from the screen

Package to import: import java.util.Scanner;

How to create a Scanner for your screen:

• Scanner xxx = new Scanner(System.in);

How to use a Scanner to read from your screen:

• int value1 = keyb.nextInt();

Methods that work on Scanner:

• nextInt()
• nextDouble()
• next() – up to next whitespace (delimiter)
• nextLine() – up to “\n”
• useDelimiter() (do not need to know)