Question

对于我的作业问题，这是一个带有签名public int applyNutrientCoefficient()的方法，用于计算Guppies中哪个Pool已经死于营养不良，并返回死亡人数。

使用Iterator<Guppy>来迭代guppiesInPool中的Pool。对于每个Guppy，使用Random方法nextDouble()生成介于0.0和1.0之间的不同随机数。如果这是随机生成的数量大于池的营养系数，杀死Guppy 通过在Guppy中设置适当的布尔字段。请注意这一点方法不会从池中移除任何死亡的孔雀鱼，它只是杀死他们。别做其他事。

我有两个班级一个是Guppy一个是Pool 在我的guppy类中，我创建了一个布尔值 -

private boolean isAlive{}
public boolean getIsAlive(){ 
    return isAlive
}

在我的Pool类....

public int applyNutrientCoefficient() 

int deathCount = 0

Iterator<Guppy> it = guppiesInPool.iterator()

while (it.hasNext() ) 

Guppy guppyOne = it.next()

    if (randomNumberGenerator.nextDouble() > nutrientCoefficient) 
    if (guppyOne.isAlive() ) 
    guppyOne.setAlive(false)
    deathCount++

    return deathCount

我收到的错误消息是找不到符号 - 方法isAlive()

有人可以帮忙吗

Answer 1

您必须通过您提供的公共getter访问isAlive私有字段getIsAlive（）

在Pool类

中

if (randomNumberGenerator.nextDouble() > nutrientCoefficient) 
if (guppyOne.isAlive() ) 
guppyOne.setAlive(false)
deathCount++

return deathCount

行

if (guppyOne.isAlive() )

应该是

if (guppyOne.getIsAlive() )

与setter相同：你需要为Guppy类提供一个setter并使用它

public void setIsAlive(boolean alive){
this.isAlive = alive}

最终结果应为

if (randomNumberGenerator.nextDouble() > nutrientCoefficient) 
if (guppyOne.getIsAlive() ) 
guppyOne.setIsAlive(false)
deathCount++

return deathCount

Answer 2

你的语法似乎有点不对劲。它应该是

public class FilterAsync extends AsyncTask {

    private FFmpegFrameGrabber VIDEO_GRABBER;
    private FFmpegFrameRecorder videoRecorder;
    private File file = new File(Environment.getExternalStorageDirectory() + "/Download/Abc.mp4");
    private Context mContext;
    private FFmpegFrameFilter filter;
    private boolean isTrue = false;
    private ArrayList<String> videoPaths;
    private File myDirectory;


    public FilterAsync(Context context) {
        mContext = context;
        VIDEO_GRABBER = new FFmpegFrameGrabber(file);
        myDirectory = new File(Environment.getExternalStorageDirectory() + "/Folder/");
        if (!myDirectory.exists()) {
            myDirectory.mkdirs();
        }
        videoPaths = new ArrayList<>();
    }


    @Override
    protected void onPreExecute() {
        super.onPreExecute();

    }

    @Override
    protected Object doInBackground(Object[] params) {
        Frame tempVideoFrame;
        try {
            VIDEO_GRABBER.start();
            initVideoRecorder(myDirectory + "/video" + System.currentTimeMillis() + ".mp4");
            filter.start();
            while (VIDEO_GRABBER.grab() != null) {
                tempVideoFrame = VIDEO_GRABBER.grabImage();
                if (tempVideoFrame != null) {
                    filter.push(tempVideoFrame);
                    tempVideoFrame = filter.pull();
                    videoRecorder.record(tempVideoFrame);
                }
            }
            videoRecorder.stop();
            filter.stop();
            videoRecorder.release();
            VIDEO_GRABBER.stop();
            VIDEO_GRABBER.release();
        } catch (FrameGrabber.Exception e) {
            e.printStackTrace();
        } catch (FrameRecorder.Exception e) {
            e.printStackTrace();
        } catch (FrameFilter.Exception e) {
            e.printStackTrace();
        }

        return null;
    }


    @Override
    protected void onPostExecute(Object o) {
        super.onPostExecute(o);
    }


    private void initVideoRecorder(String path) {
        try {
            filter = new FFmpegFrameFilter("transpose=clock ,crop=w=640:h=480:x=0:y=0", VIDEO_GRABBER.getImageWidth(), VIDEO_GRABBER.getImageHeight());

            videoRecorder = FFmpegFrameRecorder.createDefault(path, VIDEO_GRABBER.getImageWidth(), VIDEO_GRABBER.getImageHeight());
           videoRecorder.setAudioChannels(VIDEO_GRABBER.getAudioChannels());
            videoRecorder.start();
        } catch (FrameRecorder.Exception e) {
            e.printStackTrace();
        }
    }
}

然后，

private boolean isAlive; //private field, not a method.
public boolean getIsAlive() {  //public getter method.
    return isAlive;
}
public void setIsAlive(boolean isAlive) { //public setter method
    this.isAlive = isAlive;
}

还要确保使用分号和花括号，否则编译器会给你错误。

来自不同类的布尔故障

2 个答案: