Question

问题在于标题，有人可以帮助我吗？ stackoverflow上的其他类似问题对我来说并不起作用。 Android Studio告诉我＆＃34;方法不会覆盖来自超类的方法。＆＃34;，因此，我正在通过stackflow尝试不同的解决方案，例如：

将Paramters字符串，整数，字符串与我的方法匹配
尝试为方法使用不同的参数（如Void）
曾尝试编写super.onPostExecute，但Android Studio并不知道我的意思。
来自明星问题的不同程序代码

我的代码：

public class MainActivity extends AppCompatActivity {

    EditText downloadText;
    ProgressBar progressBar;
    TextView progressText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        downloadText = findViewById(R.id.downloadLink);
        progressBar = findViewById(R.id.progressBar);
        progressBar.setMax(100);
        progressBar.setIndeterminate(false);
        progressText = findViewById(R.id.progressText);
        if(shouldAskPermissions()) {
            askPermissions();
        }
    }

    public void startDownload(View view) {
        DownloadFile downloadFile = new DownloadFile();
        downloadFile.execute(downloadText.getText().toString());
    }

    public void setProgressText(int percentage) {
        progressText.setText("Download bei " + percentage + "%!");
    }

    protected boolean shouldAskPermissions() {      //Quelle: https://stackoverflow.com/questions/8854359/exception-open-failed-eacces-permission-denied-on-android
        return (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP_MR1);
    }

    @TargetApi(23)
    protected void askPermissions() {       //Quelle: https://stackoverflow.com/questions/8854359/exception-open-failed-eacces-permission-denied-on-android
        String[] permissions = {
                "android.permission.READ_EXTERNAL_STORAGE",
                "android.permission.WRITE_EXTERNAL_STORAGE"
        };
        int requestCode = 200;
        requestPermissions(permissions, requestCode);
    }

   static class DownloadFile extends AsyncTask<String, Integer, String> { // Quelle: https://www.androidhive.info/2012/04/android-downloading-file-by-showing-progress-bar/

       @Override
        public String doInBackground(String... sUrl) {
            try {
                URL url = new URL(sUrl[0]);
                URLConnection connection = url.openConnection();
                connection.connect();
                int fileLength = connection.getContentLength();
                InputStream input = new BufferedInputStream(url.openStream());
                OutputStream output = new FileOutputStream(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath()+"/" + "Test.jpg");
                byte data[] = new byte[8192];
                long total = 0;
                int count;
                while ((count = input.read(data)) != -1) {
                    total += count;
                    publishProgress((int) (total * 100 / fileLength));
                    output.write(data, 0, count);
                }
                System.out.println("Download beendet!");
                output.flush();
                output.close();
                input.close();
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }
            return null;
        }
    }

    @Override
    protected void onProgressUpdate(Integer... progress) {
        progressBar.setProgress(progress[0]);
        setProgressText(progress[0]);
    }

    @Override
    protected void onPostExecute(String result) {
        Toast.makeText(this, "Download beendet!", Toast.LENGTH_LONG).show();
    }
}

提前致谢。

Answer 1

你只需要在onProgressUpdate（）之前删除括号“}”并最后添加这个“}”：

由于这种括号方法（progressUpdate()和postExecute()）没有包含在AsyncTask中，它们被包含在Activity类中，而Activity.class没有这些覆盖方法，因此它显示错误。

    static class DownloadFile extends AsyncTask<String, Integer, String> { // Quelle: https://www.androidhive.info/2012/04/android-downloading-file-by-showing-progress-bar/

        @Override
        public String doInBackground(String... sUrl) {
            try {
                URL url = new URL(sUrl[0]);
                URLConnection connection = url.openConnection();
                connection.connect();
                int fileLength = connection.getContentLength();
                InputStream input = new BufferedInputStream(url.openStream());
                OutputStream output = new FileOutputStream(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath() + "/" + "Test.jpg");
                byte data[] = new byte[8192];
                long total = 0;
                int count;
                while ((count = input.read(data)) != -1) {
                    total += count;
                    publishProgress((int) (total * 100 / fileLength));
                    output.write(data, 0, count);
                }
                System.out.println("Download beendet!");
                output.flush();
                output.close();
                input.close();
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }
            return null;
        }
// ---- comment this        
//    }

        @Override
        protected void onProgressUpdate(Integer... progress) {
            progressBar.setProgress(progress[0]);
            setProgressText(progress[0]);
        }

        @Override
        protected void onPostExecute(String result) {
            Toast.makeText(this, "Download beendet!", Toast.LENGTH_LONG).show();
        }
//----- Add extra } here        
    }

OnProgressUpdate＆amp; OnPostExecute donet得到覆盖

1 个答案: