Question

我是一个新来的android.I有一个关于asynctaskbackground的简单代码。它不会编译。我在某些行中有问题。在doinBackground方法。我的代码是：

public class MainActivity extends ActionBarActivity {
    ProgressDialog progressBar;
    int progressincr = 1;

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

        Button startTask = (Button) findViewById(R.id.startTaskButton);
        startTask.setOnClickListener(startTaskListener);
    }
    private OnClickListener startTaskListener = new OnClickListener() {

        @Override
        public void onClick(View v) {
            Context context = getApplicationContext();
            progressBar = new ProgressDialog(v.getContext());
            BackgroundTask testBackgroundTask = new BackgroundTask();
            testBackgroundTask.execute(context);

            CharSequence text = getString(R.string.mainThreadRunning);
            int duration = Toast.LENGTH_LONG;
            Toast toast = Toast.makeText(context, text, duration);
            toast.show();

        }
    };

    private class BackgroundTask extends AsyncTask < Context, integer, string>{
        @Override
        protected void onPreExecute() {
            CharSequence message = getString(R.string.progressMessage);
            progressBar.setCancelable(true);
            progressBar.setMessage(message);
            progressBar.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            progressBar.setProgress(0);
            progressBar.setMax(100);
            progressBar.show();
        };

        @Override
        protected String doInBackground(Context... params) {
            for (int i = 0; i < 100; i = i + progressincr) {
                try { Thread.sleep(100);}

                 catch (InterruptedException e) {
                    e.printStackTrace();}

                publishProgress(progressincr);
                if(isCancelled()) break;

            }
            return getString(R.string.backgroundTaskcompleted);

        }
        protected void onProgressUpdate(Integer...values){
            progressBar.incrementProgressBy(progressincr);

        }
        protected void onPostExecute(String result){
            progressBar.dismiss();

            Context context = getApplicationContext();
            int duration = Toast.LENGTH_LONG;
            Toast toast = Toast.makeText(context,result, duration);
            toast.show();
        }

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

错误是：

  ***The method publishProgress(R.integer...) in the type       AsyncTask<Context,R.integer,R.string> is not applicable for the arguments (int) MainActivity.java   /AsyncTaskBackg/src/com/example/asynctaskbackg  line 67 Java Problem***

AND：

***Description  Resource    Path    Location    Type
The return type is incompatible with AsyncTask<Context,R.integer,R.string>.doInBackground(Context[])    MainActivity.java   /AsyncTaskBackg/src/com/example/asynctaskbackg  line 60 Java Problem***

我该如何修理它们？是什么导致的？

Answer 1

你的通用类型错了。
<Context, integer, string>必须为<Context, Integer, String>，因为泛型只接受引用，而不是值类型。此类型integer和string也不存在。基元类型为int，相应的包装类为Integer。此外，没有String类型的原始变体，因此它始终以大写字母开头 <..>中的这三个定义类型定义了返回类型或参数，引用了documentation：An asynchronous task is defined by 3 generic types, called Params, Progress and Result.，但是如果你修改了类型名称，你将会以正确的顺序使用它们。

如何在asynctask中解决错误publishprogress

1 个答案: