java - 如何在 Android 中使用 runnable 循环

Question

我正在做一个应用程序，我必须在其中显示一系列图片:顺序如下:

1. 红色 X 必须显示大约 400 毫秒；
2. 一张名为“屏幕截图”的图片必须显示大约 500 毫秒；
3. 一张名为“噪音”的图片必须展示大约 50 分钟 毫秒；
4. “噪音”图像消失，为 EditText 腾出空间。

EditText 用于获取用户数据。

这是我的代码:

public class Step1Training extends Activity {

    ImageFragment myImageFragment;
    InputFragment myInputFragment;
    Drawable cross;
    ImageView myImageView;
    EditText myEditText;
    int i, length;
    String rating;
    Handler handler;
    boolean continueTask;
    int[] screenshots = {
           R.drawable.googleplaybooks2,
           R.drawable.aldiko1,
           R.drawable.chaton2,
           R.drawable.cinetrailer1,
           R.drawable.fanpage1
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.step1_training);

        handler = new Handler();
        i = 0;
        length = screenshots.length;

        initUI();

        startThread();
    }

    private void initUI(){
        myImageFragment = (ImageFragment)getFragmentManager().findFragmentById(R.id.imageFragment);
        myInputFragment = (InputFragment)getFragmentManager().findFragmentById(R.id.inputFragment);

        myImageView = (ImageView)myImageFragment.getView().findViewById(R.id.screenshotImageView);
        myImageView.setImageResource(R.drawable.cross300x300);

        myEditText = (EditText)myInputFragment.getView().findViewById(R.id.ratingEditText);     
        myEditText.setVisibility(View.GONE);
    }

    private void startThread(){

        while(i<length){
            handler.postDelayed(new TaskScreenshot(i), 250);
            handler.postDelayed(new TaskNoise(), 750);
            handler.postDelayed(new TaskEditText(), 1000);

            myEditText.setOnKeyListener(new View.OnKeyListener(){
                public boolean onKey(View v, int keyCode, KeyEvent event) {
                    if((keyCode == KeyEvent.KEYCODE_ENTER)) {
                        if(myEditText.getText().toString().equals("")){
                            Toast.makeText(getApplicationContext(), "Inserire un numero da 1 a 9", Toast.LENGTH_SHORT).show();
                            return false;
                        } else if (Integer.parseInt(myEditText.getText().toString()) >= 1 &&
                                Integer.parseInt(myEditText.getText().toString()) <= 9){
                            return true;
                        }
                    }
                    return false;
                }
            });
            System.out.println(i);
            i++;
        }   
    }

    @Override
    public void onBackPressed() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Attenzione")
        .setMessage("Sei sicuro/a di voler uscire dall'applicazione?\n" +
                "Confermando uscirai dall'applicazione e perderai \n" +
                "tutti i dati raccolti finora.")
        .setCancelable(false)
        .setNegativeButton("No",new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int id) {
                dialog.cancel();
            }
        })
        .setPositiveButton("Si", new DialogInterface.OnClickListener()
        {
            @Override
            public void onClick(DialogInterface dialog, int whichButton)
            {
                Intent intent = new Intent(Intent.ACTION_MAIN);
                intent.addCategory(Intent.CATEGORY_HOME);
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivity(intent);
            }
        });
        AlertDialog alert = builder.create();
        alert.show();
    }

    class TaskScreenshot implements Runnable{

        int j;

        public TaskScreenshot(int _i){
            this.j = _i;
        }

        @Override
        public void run() {
            System.out.println("Screenshot");
            myEditText.setVisibility(View.GONE);
            myImageFragment.getView().setVisibility(View.VISIBLE);
            myImageView.setImageResource(screenshots[j]);
            myImageView.getLayoutParams().width = LayoutParams.MATCH_PARENT;
            myImageView.getLayoutParams().height = LayoutParams.MATCH_PARENT;
        }
    }

    class TaskNoise implements Runnable{

        @Override
        public void run() {
            System.out.println("Noise");
            myImageView.setImageResource(R.drawable.noise);
            myImageView.getLayoutParams().width = LayoutParams.MATCH_PARENT;
            myImageView.getLayoutParams().height = LayoutParams.MATCH_PARENT;
        }
    }

    class TaskEditText implements Runnable{

        @Override
        public void run() {
            System.out.println("EditText");
            myEditText.setVisibility(View.VISIBLE);
            myImageFragment.getView().setVisibility(View.GONE);
        }
    }
}

当我运行此 Activity 时，它显示红色的 X、数组的最后一个屏幕截图和噪声图像。 Logcat 显示:

0
1
2
3
4
Screenshot
Screenshot
Screenshot
Screenshot
Screenshot
Noise
Noise
Noise
Noise
Noise
EditText
EditText
EditText
EditText
EditText

我在这个循环中做错了什么？而且，我怎样才能停止循环，直到用户输入数据？

更新 1:

我已经按照用户 Groco 的建议更改了代码:

private void startThread(final int i){



    if(i < length){

                handler.postDelayed(new TaskScreenshot(i), 250);
                handler.postDelayed(new TaskNoise(), 750);
                handler.postDelayed(new TaskEditText(), 1000);

                myEditText.setOnKeyListener(new View.OnKeyListener(){
                    public boolean onKey(View v, int keyCode, KeyEvent event) {
                        if((keyCode == KeyEvent.KEYCODE_ENTER)) {
                            if(myEditText.getText().toString().equals("")){
                                Toast.makeText(getApplicationContext(), "Inserire un numero da 1 a 9", Toast.LENGTH_SHORT).show();
                                return false;
                            } else if (Integer.parseInt(myEditText.getText().toString()) >= 1 &&
                                    Integer.parseInt(myEditText.getText().toString()) <= 9){
                                System.out.println(i);
                                startThread(i+1);
                                return true;
                            }
                        }
                        return false;
                    }
                });

            }   
        }

但是当我运行它时，应用程序显示 1°、3° 和 5° 屏幕截图(索引 0、2、4)，而不是全部。我的索引有问题吗？

Answer 1

使用用户交互的结果重新启动一个周期:

 private void startThread(int i){
        if (i<length){

            handler.postDelayed(new TaskScreenshot(i), 250);
            handler.postDelayed(new TaskNoise(), 750);
            handler.postDelayed(new TaskEditText(), 1000);

            myEditText.setOnKeyListener(new View.OnKeyListener(){
                public boolean onKey(View v, int keyCode, KeyEvent event) {
                    if((keyCode == KeyEvent.KEYCODE_ENTER)) {
                        if(myEditText.getText().toString().equals("")){
                            Toast.makeText(getApplicationContext(), "Inserire un numero da 1 a 9", Toast.LENGTH_SHORT).show();
                            return false;
                        } else if (Integer.parseInt(myEditText.getText().toString()) >= 1 &&
                                Integer.parseInt(myEditText.getText().toString()) <= 9){
                            System.out.println(i);
                            i++;
                            startThread(i);
                        }
                    }
                    return false;
                }
            });

        }
        return false;
}