I am dealing with my web services and I got a strange problem and I couldn't able to solve this as I am new to android development. I am getting null pointer exception while I am showing the toast in onPostExecute()
method of async task. some one please help me to fix this
if (result.booleanValue()) // here at this line I am getting the error in logcat//
Thanks in advance....!
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
///////////male female buttons code/////////////
Button regmalebtn = (Button) findViewById(R.id.regmalebtn);
regmalebtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
gender="M";
System.out.println("gender value after male button click ="+gender);
Log.v(TAG,"gender value on male button click ="+gender );
}
});
Button regfemalebtn = (Button)findViewById(R.id.regfemalebtn);
regfemalebtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
gender ="F";
// System.out.println("gender value on female button click ="+gender);
Log.v(TAG,"gender value on female button click ="+gender );
}
});
////////////male female button code will ends here/////////////
Button signin = (Button) findViewById(R.id.regsubmitbtn);
signin.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
new RegisterTask().execute();
};
});
}
private class RegisterTask extends AsyncTask<Void, Void, Boolean> {
private final ProgressDialog dialog = new ProgressDialog(Register.this);
protected void onPreExecute() {
this.dialog.setMessage("Registering...");
this.dialog.show();
}
// @SuppressWarnings("unused")
protected Boolean doInBackground(final Void unused) {
return this.register(); //don't interact with the ui!
}
private Boolean register() {
************some code for webservices************
}
return null;
}
protected void onPostExecute(final Boolean result) {
if (this.dialog.isShowing()) {
this.dialog.dismiss();
}
if (result.booleanValue()) {
// show register success dialog
// I m getting the error at above line
Toast.makeText(Register.this, "Registerd", Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(Register.this, "Try Again", Toast.LENGTH_SHORT).show();
}
}
@Override
protected Boolean doInBackground(Void... params) {
// TODO Auto-generated method stub
return register();
}
}
}
These r the logcat errors
06-28 16:55:56.685: WARN/dalvikvm(708): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
06-28 16:55:56.695: ERROR/AndroidRuntime(708): FATAL EXCEPTION: main
06-28 16:55:56.695: ERROR/AndroidRuntime(708): java.lang.NullPointerException
06-28 16:55:56.695: ERROR/AndroidRuntime(708): at com.soap.Register$RegisterTask.onPostExecute(Register.java:193)
06-28 16:55:56.695: ERROR/AndroidRuntime(708): at com.soap.Register$RegisterTask.onPostExecute(Register.java:1)
06-28 16:55:56.695: ERROR/AndroidRuntime(708): at android.os.AsyncTask.finish(AsyncTask.java:417)
06-28 16:55:56.695: ERROR/AndroidRuntime(708): at android.os.AsyncTask.access$300(AsyncTask.java:127)
06-28 16:55:56.695: ERROR/AndroidRuntime(708): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
06-28 16:55:56.695: ERROR/AndroidRuntime(708): at android.os.Handler.dispatchMessage(Handler.java:99)
06-28 16:55:56.695: ERROR/AndroidRuntime(708): at android.os.Looper.loop(Looper.java:123)
06-28 16:55:56.695: ERROR/AndroidRuntime(708): at and开发者_如何转开发roid.app.ActivityThread.main(ActivityThread.java:4627)
You are obviously returning null from register method. Either return something that isn't null or make a null check before calling result.booleanValue()
.
You could do that like this:
if (result == null) {
}
else if (result.booleanValue()) {
}
else {
}
By the way, why do you need to return a Boolean and not boolean (primitive type, which can't be null).
Try using as argument of the Toast the name of your activity.class. I think in your case is Register.class instead of Register.this
Try passing the context into variable. Or try Register.this.getApplicationContext()
or BaseContext
. Check if the dialog is null, make the pass the values and create new dialog in the postExecute()
if that does not overlap from your requirements :)
i've written this
protected void onPostExecute(String unused) {
dismissDialog(DIALOG_DOWNLOAD_PROGRESS);
Toast.makeText(
myclassname.this,
"Downloading of " + FILENAME
+ " complete.", Toast.LENGTH_LONG).show();
refreshList();
}
and this is workning for me..
see this link for more detail
http://hi.baidu.com/hi_android/blog/item/fea149f90da7fdedfd037f56.html
http://www.screaming-penguin.com/node/7746
I got rid of the same Toast/Async/Nullpointe problem by launching Toasts like this:
Toast.makeText(getApplicationContext(), "Hello Toast!", Toast.LENGTH_SHORT).show();
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