I edited my code according dear Mayank'answer but It does not show any message that is sended as input in displayMsg() method before method begines..I should say MethodTest() is started with nfc and in method onNewIntent(Intent intent)
@Override
protected void onNewIntent(Intent intent) {
MethodTest();
..............
}
public void MethodTest() {
DisplayMsg("method 1 is running");
Method1();
DisplayMsg("method 2 is running");
Method2();
DisplayMsg("method 3 is running");
Method3();
}
private int DisplayMsg(String msg) {
totalMsg += msg;
DisplayMsgClass dc = new DisplayMsgClass();
dc.doInBackground(totalMsg);
}
private class DisplayMsgClass extends AsyncTask<String, Integer, String> {
@Override
protected void onPreExecute() {
textView.setText("Hello !!!");
progressBar = (ProgressBar) findViewById(R.id.progressBar1);
progressBar.setVisibility(View.VISIBLE);
super.onPreExecute();
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
}
@Override
protected String doInBackground(String... Messages) {
return Messages[0];
}
@Override
protected void onPostExecute(String result) {
progressBar.setVisibility(View.INVISIBLE);
textView.setText(result);
}
}
in my layout:
<LinearLayout>
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="gone"
android:id="@+id/progressBar1"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/textv1"
android:hint="AppletPass"
android:gravity="center"/>
</LinearLayout>
Remember that AsyncTasks should ideally be used for short operations (a few seconds at the most.)
Try to learn more about AsyncTask and there are so many mistakes in your code
Do not call doInBackground()
manually.
dc.doInBackground(totalMsg);
// Error
DisplayMsg() called several times, each time a new instance of class DisplayMsgClass created
DisplayMsgClass dc = new DisplayMsgClass();
// Error
onPreExecute()
textView.setText("Hello !!!");
// NullPointerException. textView.setText()
is called without initializing it.
Caution
Do not call AsyncTask.execute()
more than one on a same intance.
For eg:
DisplayMsgClass displayMsgClass = new DisplayMsgClass();
displayMsgClass.execute();
displayMsgClass.execute(); //Error, IllegalStateException
will show you a basic demo based on you implementation and you can simply modify it according to your own way.
public void MethodTest() {
// execute task
new DisplayMsgClass().execute("Download now");
}
/*
public void MethodTest() {
DisplayMsg("method 1 is running");
Method1();
DisplayMsg("method 2 is running");
Method2();
DisplayMsg("method 3 is running");
Method3();
}
private int DisplayMsg(String msg) {
totalMsg += msg;
DisplayMsgClass dc = new DisplayMsgClass();
dc.doInBackground(totalMsg);
}
*/
private class DisplayMsgClass extends AsyncTask<String, Integer, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// retrieve the widgets
progressBar = (ProgressBar) findViewById(R.id.progressBar1);
textView = (TextView) findViewById(R.id.textv1);
textView.setText("Download initialized");
progressBar.setVisibility(View.VISIBLE);
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
}
@Override
protected String doInBackground(String... Messages) {
// read commands
String command = Messages[0];
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
return "Download completed";
}
@Override
protected void onPostExecute(String result) {
//invoked on the UI thread after the background computation finishes
progressBar.setVisibility(View.INVISIBLE);
textView.setText(result);
}
}