Declaring console static and global import java.util.*; public class Test { static Scanner console = new Scanner (System.in); public static void main(String[] args) { System.out.println("Enter name"); String name = console.next(); System.out.println("Hello" + name); }

import java.lang – happens automatically – includes String, Math, wrapper classes import java.util.*; - necessary for Scanner

Public static methods All methods of Math are public and static General use of a Math method is Math.methodName (params) Or Math.pow(2,3) If you import the class statically, you can use the method directly import static java.lang.Math.*; pow(2,3)

Formal parameter – a variable declared in the method heading Actual parameter – a variable or expression listed in a method call

COSC236 Modularity5 public class Demo { public static void main(String[] args) { // Part III - strings String s = "Java is fun!"; System.out.println(s); // print it (7) sMethod(s); System.out.println(s); // print it (9) } public static void sMethod(String sTest) { sTest = sTest.substring(8, 11); // change it System.out.println(sTest); // print it (8) } Java is fun! fun Java is fun!

precaution with strings Remember - the String class is immutable String str; str = "hello"; str 1500  "hello" str = "Hello There"; str 1800  "Hello There" anytime you use assignment with a String variable, new memory space is allocated also, the String class has no methods that allow you to change an existing string COSC236 Modularity6

7 public class DemoPassByReference { public static void main(String[] args) { // Part II - objects and object references StringBuffer sb = new StringBuffer("Hello, world"); System.out.println(sb); // print it (4) sbMethod(sb); System.out.println(sb); // print it (6) System.out.println(" "); } public static void sbMethod(StringBuffer sTest) { sTest = sTest.insert(7,"cruel "); // change it System.out.println(sTest); // print it (8) } Hello, world Hello, cruel world

Wrapper classes – Integer, Double, etc are also immutable See example7-11 on p. 402