Bordcomputer/src/main/java/BordComputer.java

import device.Device;
import device.cdPlayer.CD;
import device.cdPlayer.CDPlayer;
import device.cdPlayer.CD;
import device.cdPlayer.CDPlayer;
import device.radioPlayer.RadioPlayer;
import device.usbPlayer.USB_Stick;
import device.usbPlayer.UsbPlayer;
import exception.NoItemEvenAllPreconditionAreMet;

import java.io.FileReader;
import java.lang.reflect.InvocationTargetException;
import java.util.Arrays;
import java.util.Properties;

public class BordComputer {

    String[] deviceNames;
    Device[] installedDevices;
    Device activeDevice = null;

    public void readConfig() throws ClassNotFoundException, InvocationTargetException, NoSuchMethodException, InstantiationException, IllegalAccessException {

        try (FileReader reader = new FileReader("Geraete.config")) {
            Properties properties = new Properties();
            properties.load(reader);
            String[] values = properties.values().toArray(new String[0]);
            Arrays.sort(values);
            deviceNames = new String[values.length];
            System.arraycopy(values, 0, deviceNames, 0, properties.size());
            installedDevices = new Device[values.length];
        } catch (Exception e) {
            e.printStackTrace();
        }
        setDevices();
        activeDevice = installedDevices[0];
    }

    public void setDevices() throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, ClassNotFoundException {
        Class<?> c;
        for (int i = 0; i < deviceNames.length; i++) {
            c = Class.forName(deviceNames[i]);
            installedDevices[i] = (Device) c.getConstructor().newInstance();
        }
    }

    public String changeDevice() {
        Device[] tempDevices = new Device[installedDevices.length];
        tempDevices[0] = installedDevices[1];
        tempDevices[1] = installedDevices[2];
        tempDevices[2] = installedDevices[0];
        //replaces the lists
        installedDevices = tempDevices;
        //setting activeDevice
        activeDevice = installedDevices[0];

        String infoText="";
        if(activeDevice instanceof CDPlayer){
            CDPlayer cdPlayer=(CDPlayer) activeDevice;
            String[] audioPlayList=new String[]{"Audio 01","Audio 02","Audio 03","Audio 04","Audio 05"};
            //some CDs
            CD audioCD1=new CD("Audio",audioPlayList);
            audioCD1.setAlbumName("Love Songs");

            cdPlayer.tapOnCdFlap();
            cdPlayer.setCD(audioCD1);
            cdPlayer.tapOnCdFlap();
            cdPlayer.setInfoText();
            infoText = cdPlayer.getInfoText();
        }else{
            infoText=activeDevice.getInfoText()+" ist activate";
        }
        return infoText;
    }

    public String play(){
        String itemToPlay=null;
        try {
            itemToPlay=activeDevice.play();
        }catch (RuntimeException exception) {
            throw new NoItemEvenAllPreconditionAreMet();
        }

        return itemToPlay;
    }

    //===== Hilf-Funktionen ======

    public Device getInstanceByName(String deviceName){
        for (int i = 0; i <installedDevices.length ; i++) {
            if(installedDevices[i].getClass().getSimpleName().equals(deviceName)){
                return installedDevices[i];
            }
        }
        return null;
    }
    public void meetAllPreconditionForPlay(){
        if(activeDevice instanceof CDPlayer) {
            String[] audioPlayList = new String[]{"Audio 01", "Audio 02", "Audio 03", "Audio 04", "Audio 05"};
            CD audioCD1 = new CD("Audio", "PopMusic", audioPlayList, "XAc20044");
            CD audioCD2 = new CD("Audio", "RockMusic", audioPlayList, "BLXPP78");

            CDPlayer cdPlayer = (CDPlayer) activeDevice;
            cdPlayer.changePlaySource();
            cdPlayer.loadCDWechseler(audioCD1, 0);
            cdPlayer.loadCDWechseler(audioCD2, 1);

            cdPlayer.setCD(cdPlayer.getCdWechseler().getCDList().get(0));
            activeDevice = cdPlayer;
        }
        if(activeDevice instanceof UsbPlayer) {
            USB_Stick USBDrive = new USB_Stick();
            UsbPlayer up1 = new UsbPlayer(USBDrive);
            activeDevice = up1;
        }

    }


    public void setActiveDevice(Device activeDevice) {
        this.activeDevice = activeDevice;
    }
}