处理器类

public class Cpu {public void start() {System.out.println("处理器启动了...");}
}

内存类

public class Memory {public void start() {System.out.println("内存启动了...");}
}

硬盘类

public class Disk {public void start() {System.out.println("硬盘启动了...");}
}

电脑类

public class Computer {private Cpu cpu;private Memory memory;private Disk disk;public void start() {System.out.println("电脑启动中...");cpu.start();memory.start();disk.start();System.out.println("电脑启动完毕");}
}

演示类

public class Demo {public static void main(String[] args) {Computer computer = new Computer();computer.setCpu(new Cpu());computer.setMemory(new Memory());computer.setDisk(new Disk());computer.start();}
}

演示结果