Android 自定義的控件

widget

public class DeviceSelector extends RelativeLayout implements View.OnClickListener{
    private View leftButton;
    private View rightButton;
    private View middleButton;
    private TextView title;
    private OnAfterSelectListener onAfterSelectListener;
    private int index;
    private int deviceLength;
    private ArrayList<DeviceInfo> devices;
    private ArrayList<String> deviceNameList;

    @Override
    public void onClick(View v) {
        if(null == onAfterSelectListener) return;
        switch(v.getId()){
            case R.id.devices_select_left:
                if(index == 0) {return;}
                else{
                    index = index - 1;
                    onAfterSelectListener.AfterSelect(index,devices.get(index).getDeviceName());
                    title.setText(devices.get(index).getDeviceName());
                }
                break;
            case R.id.devices_select_right:
                if(index == deviceLength-1) {return;}
                else{
                    index = index + 1;
                    onAfterSelectListener.AfterSelect(index,devices.get(index).getDeviceName());
                    title.setText(devices.get(index).getDeviceName());
                }
                break;
            case R.id.devices_select_middle:
                new MaterialDialog.Builder(this.getContext()).title("請選擇監測點")
                        .items(deviceNameList)
                        .itemsCallback(new MaterialDialog.ListCallback() {
                            @Override
                            public void onSelection(MaterialDialog dialog, View itemView, int position, CharSequence text) {
                                index = position;
                                onAfterSelectListener.AfterSelect(index,devices.get(index).getDeviceName());
                                title.setText(devices.get(index).getDeviceName());
                            }
                        })
                        .show();
                break;
        }
    }

    public interface OnAfterSelectListener{
        void AfterSelect(int index, String deviceId);
    }

    public DeviceSelector(Context context, AttributeSet attrs) {
        super(context, attrs);
        LayoutInflater.from(context).inflate(R.layout.selector_devices,this);
        leftButton = findViewById(R.id.devices_select_left);
        rightButton = findViewById(R.id.devices_select_right);
        middleButton = findViewById(R.id.devices_select_middle);
        title = (TextView) findViewById(R.id.devices_select_title);
        //Fixme 這裏是用json。
        devices = GlobalField.devices;
        deviceNameList = GlobalField.deviceNameList;
        deviceLength = devices.size();
        leftButton.setOnClickListener(this);
        rightButton.setOnClickListener(this);
        middleButton.setOnClickListener(this);
        index = 0;
        title.setText(devices.get(0).getDeviceName());
    }
    public void setOnAfterSelectListener(OnAfterSelectListener onAfterSelectListener){
        this.onAfterSelectListener = onAfterSelectListener;
    }

}

activity :

deviceSelector.setOnAfterSelectListener(new DeviceSelector.OnAfterSelectListener() {
            @Override
            public void AfterSelect(int index, String deviceId) {

            }
        });