如何在循环执行完成之前添加进度条？

Question

我正在开发一个 android 应用程序，我需要在其中显示一个 ProgressBar，直到循环执行完成。执行后会进入下一个Activity。

这是我的java代码

    public class Image_Recognition extends Activity {

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

        Button btnNextPage = (Button) findViewById(R.id.btnNextPage);


            btnNextPage.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    TextRecognizer textRecognizer = new TextRecognizer.Builder(getApplicationContext()).build();

                        Frame frame = new Frame.Builder().setBitmap(bitmap).build();
                        SparseArray<TextBlock> items = textRecognizer.detect(frame);
                        StringBuilder stringBuilder = new StringBuilder();
                        for (int i = 0; i < items.size(); ++i) {
                            TextBlock item = items.valueAt(i);
                            stringBuilder.append(item.getValue());
                            stringBuilder.append("\n");
                        }
                        stringBuilder.append('.');
                        txtResult.setText(stringBuilder.toString());


                        str = stringBuilder.toString();
                        Intent myintent = new Intent(Image_Recognition.this, ReminderAddActivity.class);
                        myintent.putExtra("translate", str);
                        startActivity(myintent);

                }
            });
        }
    //}
}

Answer 1

你可以试试这个。

final ProgressDialog dialog = new ProgressDialog(Image_Recognition.this);
btnNextPage.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {



                    dialog.show(Image_Recognition.this, "", "Please wait...", true);



                    new Handler().postDelayed(new Runnable() {
                        @Override
                        public void run() {

                            TextRecognizer textRecognizer = new TextRecognizer.Builder(getApplicationContext()).build();

                            if (!textRecognizer.isOperational())
                                Log.e("ERROR", "Detector dependencies are not yet available");
                            else {

                                Frame frame = new Frame.Builder().setBitmap(bitmap).build();
                                SparseArray<TextBlock> items = textRecognizer.detect(frame);
                                StringBuilder stringBuilder = new StringBuilder();
                                for (int i = 0; i < items.size(); ++i) {
                                    TextBlock item = items.valueAt(i);
                                    stringBuilder.append(item.getValue());
                                    stringBuilder.append("\n");
                                }
                                stringBuilder.append('.');
                                txtResult.setText(stringBuilder.toString());

                                str = stringBuilder.toString();
                            }

                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    dialog.dismiss();
                                    dialog.setCancelable(true);
                                    Intent myintent = new Intent(Image_Recognition.this, ReminderAddActivity.class);
                                    myintent.putExtra("translate", str);
                                    startActivity(myintent);
                                }
                            });
                        }
                    },5000);

Answer 2

这里有两个问题。

ProgressBar，您可以在 XML 中使用 ProgressDialog 或 ProgressBar 并显示它，同时隐藏 IU 的其余部分。

阻止用户界面

您正在直接从单击侦听器运行循环，这意味着您将阻塞您的 UI，即使您显示某种进度，它也会被阻塞直到您的循环结束，您需要启动一个线程并运行你的循环。

这是一个不太干净的点击监听器实现版本

final ProgressDialog dialog = new ProgressDialog(Image_Recognition.this);
        dialog.show();

        new Thread(new Runnable() {
            @Override
            public void run() {
                TextRecognizer textRecognizer = new TextRecognizer.Builder(getApplicationContext()).build();

                Frame frame = new Frame.Builder().setBitmap(bitmap).build();
                SparseArray<TextBlock> items = textRecognizer.detect(frame);
                StringBuilder stringBuilder = new StringBuilder();
                for (int i = 0; i < items.size(); ++i) {
                    TextBlock item = items.valueAt(i);
                    stringBuilder.append(item.getValue());
                    stringBuilder.append("\n");
                }
                stringBuilder.append('.');
                txtResult.setText(stringBuilder.toString());

                str = stringBuilder.toString();

                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        dialog.dismiss();
                        Intent myintent = new Intent(Image_Recognition.this, ReminderAddActivity.class);
                        myintent.putExtra("translate", str);
                        startActivity(myintent);
                    }
                });
            }
        }).start();

Answer 3

您可以使用异步任务并在 doInBackground() 中运行循环

class MyTask extends AsyncTask<Void, Void, Void> {
    ProgressDialog pd;
    public MyTask(ProgressDialog pd){
        this.pd=pd;
    }
    @Override
    protected void onPreExecute () {
        super.onPreExecute();
        pd.setMessage("Uploading . . .");
        pd.show();
        pd.setCancelable(false);
    }

    @Override
    protected Void doInBackground (Void...voids){
        for(int i=0;i<10000000;i++){
            System.out.print(i);
        }
        return null;//download file
    }

    @Override
    protected void onPostExecute (Void aVoid){
        super.onPostExecute(aVoid);
        pd.dismiss();
    }
}

并在活动中调用new MyTask(pd).execute();