Pada praktikum kelima ini dijelaskan tentang “Strategy Pattern” dan materi ini , yaitu dijelaskan sedikit tentang design pattern. Pada pertemuan ini dibahas kembali tentang materi pertemuan sebelumnya, kemudian ditambah tentang penggunaan Exception Handling dan Trows.
Berikut adalah kode program Strategy Pattern :
Pertama kita buat dulu GoAlgorithm.java sebagai interface-nya dengan method go(), yang belum di implementasikan.
package StrategyPattern;
public interface GoAlgorithm {
public void go();
}
Setelah itu kita buat class-class implemennya
package StrategyPattern;
public class GoByDrivingAlgorithm implements GoAlgorithm {
public void go() {
System.out.println("Now i'm Driving");
}
}
package StrategyPattern;
public class GoByFlyingAlgorithm implements GoAlgorithm {
public void go() {
System.out.println("Now i'm Flying");
}
}
package StrategyPattern;
public class GoByFlyingFastAlgorithm implements GoAlgorithm {
public void go() {
System.out.println("Now i'm Flying Fast");
}
}
Setelah itu kita buat class-class turunannya, sbb:
package StrategyPattern;
public class FormulaOne extends Vehicle {
public FormulaOne() {
setGoAlgorithm(new GoByDrivingAlgorithm());
}
}
package StrategyPattern;
public class Helicopter extends Vehicle {
public Helicopter() {
setGoAlgorithm(new GoByFlyingAlgorithm());
}
}
package StrategyPattern;
public class Jet extends Vehicle {
public Jet() {
setGoAlgorithm(new GoByFlyingFastAlgorithm());
}
}
package StrategyPattern;
public class StreetRacer extends Vehicle {
public StreetRacer() {
setGoAlgorithm(new GoByDrivingAlgorithm());
}
}
package StrategyPattern;
public class Vehicle {
private GoAlgorithm goAlgorithm;
public Vehicle() {
}
public void setGoAlgorithm(GoAlgorithm algorithm) {
this.goAlgorithm = algorithm;
}
public void go() {
goAlgorithm.go();
}
}
Lalu terakhir, fungsi main-nya ini :
package StrategyPattern;
import javax.swing.JOptionPane;
public class StartTheRacer {
public static void main(String[] args) {
StreetRacer streetRacer = new StreetRacer();
FormulaOne formulaOne = new FormulaOne();
Helicopter helicopter = new Helicopter();
Jet jet = new Jet();
streetRacer.go();
formulaOne.go();
helicopter.go();
jet.go();
}
}
Kemudian dijelaskan tentang Exception Handling, berikut kode programnya :
package ExceptionHandling;
public class DivByZero {
public static void main(String[] args) {
System.out.println(3 / 0);
System.out.println("Cetak");
}
}
package ExceptionHandling;
import javax.swing.JOptionPane;
public class DivByZeroWithTry {
public static void main(String[] args) {
try {
System.out.println(3 / 0);
System.out.println("Cetak");
} catch (ArithmeticException e) {
JOptionPane.showMessageDialog(null, "Error : Devided by Zero!",
"ERROR", JOptionPane.ERROR_MESSAGE);
} catch (ArrayIndexOutOfBoundsException a) {
JOptionPane.showMessageDialog(null, "Missing Argument.",
"ERROR", JOptionPane.ERROR_MESSAGE);
}
System.out.println("Setelah Exception.");
System.exit(0);
}
}
package ExceptionHandling;
public class FinallyDemo {
public static void main(String[] args) {
int i = 0;
String[] greeting = {
"hallo pagi", "cagur", "test lagi"
};
while (i < 4) {
try {
System.out.println(greeting[i]);
i++;
} catch (ArrayIndexOutOfBoundsException e) {
System.out.println("index value");
i++;
//i=0;
} finally {
System.out.println("FINAL");
}
}
}
}
Kemudian terakhir adalah tentang penggunaan Throw :
package Trows;
public class Throw {
static void MyTrow() throws ClassNotFoundException {
throw new ClassNotFoundException("just a demo");
}
}
package Trows;
public class ThrowDemo {
public static void main(String[] args) {
try {
Throw.MyTrow();
} catch (ClassNotFoundException e) {
System.out.println(e);
}
}
}
Ecko
