Facade Design pattern in java

Facade design pattern is a pattern that is used to provide a simple interface to a large amount of code. This makes it very easy to use libraries in programming language. The following example is taken from http://en.wikipedia.org/wiki/Facade_pattern.


/* Complex parts */
class CPU {
public void freeze() { ... }
public void jump(long position) { ... }
public void execute() { ... }
}

class Memory {
public void load(long position, byte[] data) { ... }
}

class HardDrive {
public byte[] read(long lba, int size) { ... }
}

/* Facade */

class Computer {
private CPU cpu;
private Memory memory;
private HardDrive hardDrive;
public Computer() {
this.cpu = new CPU();
this.memory = new Memory();
this.hardDrive = new HardDrive();
}

public void startComputer() {
cpu.freeze();
memory.load(BOOT_ADDRESS, hardDrive.read(BOOT_SECTOR, SECTOR_SIZE));
cpu.jump(BOOT_ADDRESS);
cpu.execute();
}
}

/* Client */

class You {
public static void main(String[] args) {
Computer facade = new Computer();
facade.startComputer();
}
}