1. Basic Utility Classes U Abd. Rohim, MT mailto: info@abdrohim.com
Website/Blog:
Basic Utility Classes

2. Packages of the Java API
java.lang = Basic language classes
java.lang.reflect = Reflection
java.io = Input and output
java.util = Utilities and collections classes
java.text = International text classes
java.net = Sockets and URLs
java.applet = The applet API
javax.swing, java.awt = Swing and 2D graphics
javax.swing.event, java.awt.event = Event classes
java.awt.image = 2D image-processing classes
java.beans = JavaBeans API
java.rmi = RMI classes
U Abd. Rohim,
Java
(Basic Utility Classes)

3. (Basic Utility Classes)
The java.lang package
Java.lang
Java.io
Boolean
Character
Object
Math
Byte
Double
Number
Float
String
Integer
StringBuffer
Long
System
Short
U Abd. Rohim,
Java
(Basic Utility Classes)

4. (Basic Utility Classes)
The java.util package
Java.lang
Java.util
Java.io
BitSet
Calendar
GregorianCalendar
Object
Date
SimpleTimeZone
TimeZone
Stack
Vector
StringBuffer
System
U Abd. Rohim,
Java
(Basic Utility Classes)

5. (Basic Utility Classes)
String In Java
Class
String
StringBuffer
Constructor
Contoh 1
String aString
aString = “Ini String”;
Contoh 2
String aString =“Ini String”;
Contoh 3
String aString New String(“Ini String”);
Contoh 4
String str New String();
String str = “”;
U Abd. Rohim,
Java
(Basic Utility Classes)

6. (Basic Utility Classes)
String Method
charAt( )
compareTo( )
concat( )
copyValueOf( )
endsWith( )
equals( )
equalsIgnore-Case()
getBytes( )
getChars( )
hashCode( )
indexOf( )
intern( )
lastIndexOf( )
length( )
regionMatches( )
replace( )
startsWith( )
substring( )
toCharArray( )
toLowerCase( )
toString( )
toUpperCase( )
trim( )
valueOf( )
StringBuffer
Length()
Capacity()
Insert()
Append()
U Abd. Rohim,
Java
(Basic Utility Classes)

7. (Basic Utility Classes)
Tipe Bilangan
Java menyediakan tipe bilangan primitif (int, char, float) sebagai sesuatu non class
Terdapat Kelas Wrapper untuk tipe primitif (dibedakan dg huruf kapitat diawal)
Double size = new Double ( );
double d = size.doubleValue( ); // 32.76
float f = size.floatValue( ); // 32.76
long l = size.longValue( ); // 32
int i = size.intValue( ); // 32
U Abd. Rohim,
Java
(Basic Utility Classes)

8. (Basic Utility Classes)
Math Methode
Math.abs(a)
Math.acos(a)
Math.asin(a)
Math.atan(a)
Math.atan2(a,b)
Math.ceil(a)
Math.cos(a)
Math.exp(a)
Math.floor(a)
Math.log(a)
Math.max(a, b)
Math.min(a, b)
Math.pow(a, b)
Math.random( )
Math.rint(a)
Math.round(a)
Math.sin(a)
Math.sqrt(a)
Math.tan(a)
U Abd. Rohim,
Java
(Basic Utility Classes)

9. (Basic Utility Classes)
Beberapa Contoh Lain
double irrational = Math.sqrt( 2.0 );
int bigger = Math.max( 3, 4 );
long one = Math.round( );
double circumference = diameter * Math.PI;
Vector myNumbers = new Vector( );
Integer thirtyThree = new Integer( 33 );
myNumbers.addElement( thirtyThree );
Integer theNumber = (Integer)myNumbers.firstElement( );
int n = theNumber.intValue( ); // 33
U Abd. Rohim,
Java
(Basic Utility Classes)

10. (Basic Utility Classes)
Date
Terdapat pada class java.util.Date
Contoh program class calendar
Calendar c = Calendar.getInstance( ); // today
System.out.println("Year: " + c.get(Calendar.YEAR));
System.out.println("Month: " + c.get(Calendar.MONTH));
System.out.println("Day: " + c.get(Calendar.DAY_OF_MONTH));
System.out.println("Day of week = " + c.get(Calendar.DAY_OF_WEEK));
System.out.println("Day of year = " + c.get(Calendar.DAY_OF_YEAR));
System.out.println("Week in Year: " + c.get(Calendar.WEEK_OF_YEAR));
System.out.println("Week in Month: " + c.get(Calendar.WEEK_OF_MONTH));
System.out.println("Day of Week in Month: " +
c.get(Calendar.DAY_OF_WEEK_IN_MONTH));
System.out.println("Hour: " + c.get(Calendar.HOUR));
System.out.println("AM or PM: " + c.get(Calendar.AM_PM));
System.out.println("Hour (24-hour clock): " +
c.get(Calendar.HOUR_OF_DAY));
System.out.println("Minute: " + c.get(Calendar.MINUTE));
System.out.println("Second: " + c.get(Calendar.SECOND));
U Abd. Rohim,
Java
(Basic Utility Classes)

11. DateFormat format codes
G = Era designator
y = Year
M = Month in year
d = Day in month
h = Hour in A.M./P.M. (1~12)
H = Hour in day (0~23)
m = Minute in hour
s = Second in minute
S = Millisecond
E = Day in week
D = Day in year
F = Day of week in month
w = Week in year
W = Week in month
a = A.M./P.M. marker
k = Hour in day (1~24)
K = Hour in A.M./P.M. (0~11)
z = Time zone
' = Escape for text
" = Single quote
// DateDemo.java
Date dNow = new Date( );
/* Simple, Java 1.0 date printing */
System.out.println("It is now " + dNow.toString( ));
// Use a SimpleDateFormat to print the date our way.
SimpleDateFormat formatter
= new SimpleDateFormat ("E yyyy.MM.dd 'at' hh:mm:ss a zzz");
System.out.println("It is " + formatter.format(dNow));
U Abd. Rohim,
Java
(Basic Utility Classes)

12. (Basic Utility Classes)
Timers
Terdapat dua kelas: java.util.Timer, java.util.TimerTask
Contoh Program
import java.util.*;
public class Y2K {
public static void main(String[] args) {
Timer timer = new Timer( );
TimerTask task = new TimerTask( ) {
public void run( ) {
System.out.println("Boom!"); } };
Calendar c = new GregorianCalendar(2000, Calendar.JANUARY, 1);
timer.schedule(task, c.getTime( ));
U Abd. Rohim,
Java
(Basic Utility Classes)