i got an error Attempt to invoke virtual method 'android.support.v7.app.AlertDialog android.support.v7.app.AlertDialog$Builder.create()' on a null object reference
everytime i build my app
here's code of my error
07-26 15:04:32.587 18897-18915/com.example.study E/AndroidRuntime: FATAL EXCEPTION: Thread-385
Process: com.example.study, PID: 18897
java.lang.NullPointerException: Attempt to invoke virtual method 'android.support.v7.app.AlertDialog android.support.v7.app.AlertDialog$Builder.create()' on a null object reference
at com.example.study.Splash.checking(Splash.java:66)
at com.example.study.Splash$2.run(Splash.java:51)
it happened on my splash activity, here's my code
package com.example.study;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import com.example.study.helper.SessionManager;
import com.example.study.util.ConnectionDetector;
public class Splash extends AppCompatActivity {
private ConnectionDetector cd;
Boolean isInternetPresent = false;
protected SessionManager session;
private AlertDialog.Builder builder;
@Override
protected void onCreate (Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splash);
AlertDialog.Builder builder = new AlertDialog.Builder(Splash.this);
session = new SessionManager(getApplicationContext());
cd = new ConnectionDetector(getApplicationContext());
builder.setTitle("No Connection");
builder.setMessage("Check Your Internet Connection.");
builder.setIcon(R.drawable.fail);
builder.setPositiveButton("OK", new
DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int id) {
/* TODO Auto-generated method stub */
dialog.dismiss();
}
});
Thread timer = new Thread(){
public void run(){
try {
sleep(2000);
} catch (Exception e) {
e.printStackTrace();
} finally {
checking();
}
}
};
timer.start();
}
public void checking() {
isInternetPresent = cd.isConnectingToInternet();
if(isInternetPresent) {
session.checkLogin();
finish();
} else {
builder.create().show();
finish();
}
}
}
dunno what to do ... please help to solve this problem,
I think it fails at your checking()
method. You have declared a global variable named builder
, then you declared another variable inside your onCreate()
. In your checking()
method, it refers to the global variable which you didn't initialize, only declare.
Possible solution, edit this :
AlertDialog.Builder builder = new AlertDialog.Builder(Splash.this);
to
builder = new AlertDialog.Builder(Splash.this);
Please use this below code for reference, it's working fine for me.
Before onCreate()
AlertDialog.Builder alertDialog;
Within OnCreate()
alertDialog = new AlertDialog.Builder(YourActivity.this);
Create AlertDialog
alertDialog.setMessage("Do you want to continue ?");
alertDialog.setPositiveButton("YES", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//write your code here after click yes
}
});
alertDialog.setNegativeButton("NO", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
alertDialog.show();
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