We Keep Coding

I am trying to navigate to multiple activities using intents and i am getting a run time exception, I am a beginner with eclipse , so please guide me

MainActivity.java
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText txtUserName = (EditText)findViewById(R.id.editText1);
final EditText txtPassword = (EditText)findViewById(R.id.editText2);
Button btnLogin = (Button)findViewById(R.id.button1);
btnLogin.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v) {
String username = txtUserName.getText().toString();
String password = txtPassword.getText().toString();
String foo = new String("131031001");
String foo2 = new String("131031002");
String foo3 = new String("131031003");
String foo4 = new String("131031004");
String foo5 = new String("131031005");
try{
if(username.length() > 0 && password.length() >0) {
DBUserAdapter dbUser = new DBUserAdapter(MainActivity.this);
dbUser.open();
dbUser.AddUser();
if(dbUser.Login(username, password))
{
Toast.makeText(MainActivity.this,"Successfully Logged In", Toast.LENGTH_LONG).show();
if(username.equals(foo))
{
Intent nextActivity2 = new Intent(getApplicationContext(),SecondActivity.class);
nextActivity2.putExtra("Second",username);
startActivity(nextActivity2);
}
else if(username.equals(foo2)) {
Intent nextActivity3 = new Intent(getBaseContext(),ThirdActivity.class);
nextActivity3.putExtra("Third",username);
startActivity(nextActivity3);
}
else if(username.equals(foo3))
{
Intent nextActivity4 = new Intent(getBaseContext(),FourthActivity.class);
nextActivity4.putExtra("Fourth",username);
startActivity(nextActivity4);
}
else if(username.equals(foo4)) {
Intent nextActivity5 = new Intent(getBaseContext(),FifthActivity.class);
nextActivity5.putExtra("Fifth",username);
startActivity(nextActivity5);
}
else if(username.equals(foo5)) {
Intent nextActivity6 = new Intent(getBaseContext(),SixthActivity.class);
nextActivity6.putExtra("Sixth",username);
startActivity(nextActivity6);
}
else {
Toast.makeText(MainActivity.this,"Result does not exist! Try later!!", Toast.LENGTH_LONG).show();
}
}else {
Toast.makeText(MainActivity.this,"Invalid Username/Password", Toast.LENGTH_LONG).show();
}
dbUser.close();
}
}catch(Exception e) {
Toast.makeText(MainActivity.this,e.getMessage(), Toast.LENGTH_LONG).show();
}
}
});
Button btreg = (Button)findViewById(R.id.button2);
btreg.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v) {
Intent nextActivity = new Intent(getApplicationContext(),Register.class);
startActivity(nextActivity);
}
});
}
}
SecondActivity.java
public class SecondActivity extends Activity {
Intent intent = getIntent();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_activity);
}
}
All other activities are coded similar to the above.
Here is my logcat.
10-28 14:53:10.688: E/AndroidRuntime(1196): Process: com.skcetresults, PID: 1196
10-28 14:53:10.688: E/AndroidRuntime(1196): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.skcetresults/com.skcetresults.SecondActivity}: java.lang.NullPointerException
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2176)
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.app.ActivityThread.access$700(ActivityThread.java:135)
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.os.Handler.dispatchMessage(Handler.java:102)
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.os.Looper.loop(Looper.java:137)
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.app.ActivityThread.main(ActivityThread.java:4998)
10-28 14:53:10.688: E/AndroidRuntime(1196): at java.lang.reflect.Method.invokeNative(Native Method)
10-28 14:53:10.688: E/AndroidRuntime(1196): at java.lang.reflect.Method.invoke(Method.java:515)
10-28 14:53:10.688: E/AndroidRuntime(1196): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
10-28 14:53:10.688: E/AndroidRuntime(1196): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
10-28 14:53:10.688: E/AndroidRuntime(1196): at dalvik.system.NativeStart.main(Native Method)
10-28 14:53:10.688: E/AndroidRuntime(1196): Caused by: java.lang.NullPointerException
10-28 14:53:10.688: E/AndroidRuntime(1196): at com.skcetresults.SecondActivity.onCreate(SecondActivity.java:15)
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.app.Activity.performCreate(Activity.java:5243)
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-28 14:53:10.688: E/AndroidRuntime(1196): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140)
10-28 14:53:10.688: E/AndroidRuntime(1196): ... 11 more
With just two intents the code worked fine, but when I'm comparing the value with strings, the app crashes, I don't know where the bug is.

Instead of getBaseContext() and getApplicationContext(), use MainActivity.this as context, will work everywhere.

You should put it like this
public class SecondActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_activity);
Intent i = getIntent();
}
}
If the extra data are strings you can get it like this:
String nameString = i.getStringExtra("nameExtra");

You can't use getIntent() before onCreate(), there's simply no Intent available at that point.
In your code, I suspect that you are trying to get StringExtras from Intent, But as intent is null, it is throwing NullPointerException.
In your Second Activity you can use getIntent() in onCreate() method.
public class SecondActivity extends Activity {
Intent intent;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_activity);
intent = getIntent();
String userName = intent.getStringExtra("Second");
...
}
}

Use little pieces of code checking, to ensure your intent behaves properly. For example, you could surround your getIntent code with an if statement. For which proper method to call, you have to wander around a bit, as this depends on what you want your app to do. Fortunately, Eclipse delivers you all the related documentation, when you write down some piece of Android resources, e.g. Intent.

Force close when setting onclick

I created a button and assigned it 1 by doing
remove.setId(0 + count);
Then I tried to put that button in my onCreate bundle to use it
Button remove = (Button)findViewById(1);
remove.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
When I create the button remove in my oncreate it runs but as soon as I add my onclick listener I dont get any errors but when I run it it force closes
Log
12-12 13:42:06.172: D/AndroidRuntime(19502): Shutting down VM
12-12 13:42:06.172: W/dalvikvm(19502): threadid=1: thread exiting with uncaught exception (group=0x416bbd40)
12-12 13:42:06.178: E/AndroidRuntime(19502): FATAL EXCEPTION: main
12-12 13:42:06.178: E/AndroidRuntime(19502): Process: com.th3ramr0d.armytrooptotask, PID: 19502
12-12 13:42:06.178: E/AndroidRuntime(19502): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.th3ramr0d.armytrooptotask/com.th3ramr0d.armytrooptotask.MainActivity}: java.lang.NullPointerException
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2269)
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.app.ActivityThread.access$800(ActivityThread.java:139)
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.os.Handler.dispatchMessage(Handler.java:102)
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.os.Looper.loop(Looper.java:136)
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.app.ActivityThread.main(ActivityThread.java:5102)
12-12 13:42:06.178: E/AndroidRuntime(19502): at java.lang.reflect.Method.invokeNative(Native Method)
12-12 13:42:06.178: E/AndroidRuntime(19502): at java.lang.reflect.Method.invoke(Method.java:515)
12-12 13:42:06.178: E/AndroidRuntime(19502): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
12-12 13:42:06.178: E/AndroidRuntime(19502): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
12-12 13:42:06.178: E/AndroidRuntime(19502): at dalvik.system.NativeStart.main(Native Method)
12-12 13:42:06.178: E/AndroidRuntime(19502): Caused by: java.lang.NullPointerException
12-12 13:42:06.178: E/AndroidRuntime(19502): at com.th3ramr0d.armytrooptotask.MainActivity.onCreate(MainActivity.java:45)
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.app.Activity.performCreate(Activity.java:5248)
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1110)
12-12 13:42:06.178: E/AndroidRuntime(19502): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2173)
12-12 13:42:06.178: E/AndroidRuntime(19502): ... 11 more
Here is my full file
package com.th3ramr0d.armytrooptotask;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.text.Editable;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.Toast;
public class MainActivity extends Activity {
public int count = 1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button addTroopBtn = (Button) findViewById(R.id.addTroop);
addTroopBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(count <= 5)
{
inputName(v);
}
else
{
}
}
});
Button remove = (Button)findViewById(1);
remove.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
}
public void inputName(final View v){
AlertDialog.Builder alert = new AlertDialog.Builder(this);
//alert.setTitle("Enter Name and Rank");
alert.setMessage("Please Enter A Name");
// Set an EditText view to get user input
final EditText input = new EditText(this);
alert.setView(input);
alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
Editable name = input.getText();
addTroop(name);
}
});
alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
// Canceled.
}
});
alert.show();
}
public void addTroop(Editable name){
LinearLayout mainPage = (LinearLayout) findViewById(R.id.manageTroopsMain);
if (count <= 5)
{
//CREATE NEW LINEAR LAYOUT
LinearLayout addTroopLayout = new LinearLayout(this);
//CREATE LAYOUT PARAMS FOR LAYOUT
LinearLayout.LayoutParams newLayout = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
newLayout.bottomMargin = 10;
//STYLE NEW LINEAR LAYOUT
addTroopLayout.setTag("addTroopLayout" + count);
addTroopLayout.setLayoutParams(newLayout);
addTroopLayout.setOrientation(LinearLayout.HORIZONTAL);
//CREATE NEW BUTTONS
Button newTroop = new Button(this);
Button remove = new Button(this);
Button change = new Button(this);
//CREATE LAYOUT PARAMS FOR BUTTONS
LinearLayout.LayoutParams newTroopParam = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 20f);
LinearLayout.LayoutParams rmvBtnParam = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, .5f);
LinearLayout.LayoutParams chngNameParam = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, .5f);
//STYLE NEW BUTTONS
newTroop.setText(name);
newTroop.setGravity(Gravity.LEFT|Gravity.CENTER_VERTICAL);
newTroop.setLayoutParams(newTroopParam);
remove.setId(0 + count);
remove.setText("-");
remove.setGravity(Gravity.CENTER_HORIZONTAL|Gravity.CENTER_VERTICAL);
remove.setLayoutParams(rmvBtnParam);
change.setText("...");
change.setGravity(Gravity.CENTER_HORIZONTAL|Gravity.CENTER_VERTICAL);
change.setLayoutParams(chngNameParam);
//ADD VIEWS TO NEW LAYOUT
addTroopLayout.addView(newTroop);
addTroopLayout.addView(remove);
addTroopLayout.addView(change);
//ADD NEW LAYOUT TO mainPage LAYOUT
mainPage.addView(addTroopLayout);
//Increment Counter
count++;
}
}
}

This is your problem:
Button remove = (Button)findViewById(1);
This should be something like this:
Button remove = (Button)findViewById(R.id.buttonRemove); // that should be a long int

The crash is likely happening from this line:
Button remove = (Button)findViewById(1);
You'll need to provide a valid ID for a Button within your inflated layout. A value of 1 is not meaningful.

Android Application "Source Not Found" java.lang.runtimeexception

I switched from running my app on a phone to a nexus 10 tablet and now it says "unfortunately the application has stopped."
The tablet is running 4.4.2, my target api is set to 19 in the manifest.
When I run it in debug mode I get Source Not Found. I tried clicking edit source lookup path and adding my project and had no luck.
I've looked all over the internet and haven't had any luck solving this problem. Any suggestions would be a big help.
"java.lang.RuntimeException: Unable to start activity ComponentInfo{com.looper.video/com.looper.video.MainActivity}: java.lang.NullPointerException"
Edit:
MainActivity:
package com.looper.video;
public class MainActivity extends Activity {
private VideoView video;
private MediaController ctlr;
final Uri firstVideoPath = Uri.parse("android.resource://com.looper.video/" + R.raw.wildlife);
final Uri secondVideoPath = Uri.parse("android.resource://com.looper.video/" + R.raw.wildlife1);
private String videosPath = Environment.getExternalStorageDirectory() + "/videos/";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
File folder = new File(videosPath);
File[] customFiles = folder.listFiles();
List<String> customFileNames = new ArrayList<String>();
for(File file : customFiles) {
customFileNames.add(file.getName());
}
ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(
this, android.R.layout.simple_spinner_item, customFileNames);
spinnerArrayAdapter.setDropDownViewResource( android.R.layout.simple_spinner_dropdown_item );
Spinner spinner = (Spinner)findViewById(R.id.spinnerCustomFiles);
spinner.setAdapter(spinnerArrayAdapter);
video = (VideoView)findViewById(R.id.videoView1);
ctlr = new MediaController(this);
final Button firstVideoBtn = (Button) findViewById(R.id.firstVideoBtn);
firstVideoBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
playFirstVideo();
}
});
final Button secondVideoBtn = (Button) findViewById(R.id.secondVideoBtn);
secondVideoBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
playSecondVideo();
}
});
}
public void playFeatured(View v) {
try {
Spinner spinner = (Spinner)findViewById(R.id.spinnerCustomFiles);
String strPath = videosPath + spinner.getSelectedItem().toString();
Toast.makeText(this, strPath, Toast.LENGTH_LONG).show();
//Uri path = Uri.parse(videosPath + spinner.getSelectedItem().toString());
video.setVideoPath(strPath);
ctlr.setMediaPlayer(video);
video.setMediaController(ctlr);
video.requestFocus();
video.start();
video.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
#Override
public void onCompletion(MediaPlayer vmp) {
playSecondVideo();
}
});
} catch(Exception e) {
System.out.println(e.getMessage());
}
}
public void playFirstVideo() {
video.setVideoURI(firstVideoPath);
ctlr.setMediaPlayer(video);
video.setMediaController(ctlr);
video.requestFocus();
video.start();
video.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
#Override
public void onCompletion(MediaPlayer vmp) {
playSecondVideo();
}
});
}
public void playSecondVideo() {
SharedPreferences sp = getSharedPreferences("schedule", Context.MODE_PRIVATE);
//SimpleDateFormat sdf = new SimpleDateFormat("hh:mm");
String startTime = sp.getString("startTime", "");
String endTime = sp.getString("endTime", "");
/*
//SimpleDateFormat parser = new SimpleDateFormat("HH:mm");
//Date dateStartTime = parser.parse(startTime);
//Date dateEndTime = parser.parse(endTime);
Date now = new Date();
try {
if (userDate.after(ten) && userDate.before(eighteen)) {
}
} catch (ParseException e) {
// Invalid date was entered
}
System.out.println("Now:"+now);
System.out.println("Start"+startTime);
System.out.println("End:"+endTime);
//if(now.before(dateEndTime) && now.after(dateStartTime)){
//disableAll();
//} else {
*
*/
video.setVideoURI(secondVideoPath);
ctlr.setMediaPlayer(video);
video.setMediaController(ctlr);
video.requestFocus();
video.start();
video.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
#Override
public void onCompletion(MediaPlayer vmp) {
playSecondVideo();
}
});
//}
}
public void admin(View view)
{
//MySQLiteHelper db = new MySQLiteHelper(this);
//final String password = db.getUser(7).getPassword();
//db.close();
final AlertDialog.Builder alert = new AlertDialog.Builder(this);
final EditText pass = new EditText(this);
alert.setView(pass);
alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
String value = pass.getText().toString().trim();
SharedPreferences sp1 = getSharedPreferences("Login", 0);
//String username = sp1.getString("UserName", "");
String password = sp1.getString("Password", "");
if(value.equals(password)) {
Intent intent = new Intent(getBaseContext(),Admin.class);
startActivity(intent);
}
//Toast.makeText(getApplicationContext(), password + " " + value, Toast.LENGTH_SHORT).show();
}
});
alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
dialog.cancel();
}
});
alert.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);
}
public void disableAll(){
Button firstVideoBtn = (Button)findViewById(R.id.firstVideoBtn);
firstVideoBtn.setEnabled(false);
Button secondVideoBtn = (Button)findViewById(R.id.secondVideoBtn);
secondVideoBtn.setEnabled(false);
Spinner spinner = (Spinner)findViewById(R.id.spinnerCustomFiles);
spinner.setEnabled(false);
Button btnPlay = (Button)findViewById(R.id.btnPlayFeatured);
btnPlay.setEnabled(false);
VideoView videoView = (VideoView)findViewById(R.id.videoView1);
videoView.setEnabled(false);
}
}
Full logcat:
D/dalvikvm(2817): GC_FOR_ALLOC freed 58K, 4% free 3441K/3568K, paused 20ms, total 20ms
10-08 15:23:17.965: D/dalvikvm(2817): GC_FOR_ALLOC freed 2K, 4% free 3505K/3632K, paused 7ms, total 7ms
10-08 15:23:17.975: I/dalvikvm-heap(2817): Grow heap (frag case) to 8.739MB for 5515216-byte allocation
10-08 15:23:17.985: D/dalvikvm(2817): GC_FOR_ALLOC freed <1K, 2% free 8891K/9020K, paused 7ms, total 7ms
10-08 15:23:18.055: D/AndroidRuntime(2817): Shutting down VM
10-08 15:23:18.055: W/dalvikvm(2817): threadid=1: thread exiting with uncaught exception (group=0x4155eba8)
10-08 15:23:18.055: E/AndroidRuntime(2817): FATAL EXCEPTION: main
10-08 15:23:18.055: E/AndroidRuntime(2817): Process: com.looper.video, PID: 2817
10-08 15:23:18.055: E/AndroidRuntime(2817): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.looper.video/com.looper.video.MainActivity}: java.lang.NullPointerException
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.app.ActivityThread.access$800(ActivityThread.java:135)
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.os.Handler.dispatchMessage(Handler.java:102)
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.os.Looper.loop(Looper.java:136)
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.app.ActivityThread.main(ActivityThread.java:5017)
10-08 15:23:18.055: E/AndroidRuntime(2817): at java.lang.reflect.Method.invokeNative(Native Method)
10-08 15:23:18.055: E/AndroidRuntime(2817): at java.lang.reflect.Method.invoke(Method.java:515)
10-08 15:23:18.055: E/AndroidRuntime(2817): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
10-08 15:23:18.055: E/AndroidRuntime(2817): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
10-08 15:23:18.055: E/AndroidRuntime(2817): at dalvik.system.NativeStart.main(Native Method)
10-08 15:23:18.055: E/AndroidRuntime(2817): Caused by: java.lang.NullPointerException
10-08 15:23:18.055: E/AndroidRuntime(2817): at com.looper.video.MainActivity.onCreate(MainActivity.java:52)
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.app.Activity.performCreate(Activity.java:5231)
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-08 15:23:18.055: E/AndroidRuntime(2817): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
10-08 15:23:18.055: E/AndroidRuntime(2817): ... 11 more

Cant start a dialog activity from a button in another activity

I am trying to start a new activity as a Dialog Activity putting a Intent on a button from another activity. Whenever I try and press the button, the activity unfotunately closes.
Main Activity.java
public class MainActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button ab = (Button) findViewById(R.id.button1);
ab.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent intent = new Intent(MainActivity.this, NewDialog.class);
startActivity(intent);
}
#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;
}
public void side(View view){
android.support.v4.app.FragmentManager fm1 = getSupportFragmentManager();
NewDialog newdialog = new NewDialog();
newdialog.show(fm1, "SideDialog");
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
}
NewDialog.java
public class NewDialog extends DialogFragment{
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState){
final View view = inflater.inflate(R.layout.activity_new_dialog, container);
getDialog().requestWindowFeature(Window.FEATURE_NO_TITLE);
return view;
}
}
Added Logcat:
05-29 22:37:36.472: D/dalvikvm(26806): Late-enabling CheckJNI
05-29 22:37:36.762: D/ActivityThread(26806): setTargetHeapUtilization:0.25
05-29 22:37:36.762: D/ActivityThread(26806): setTargetHeapIdealFree:8388608
05-29 22:37:36.762: D/ActivityThread(26806): setTargetHeapConcurrentStart:2097152
05-29 22:37:39.172: D/libEGL(26806): loaded /system/lib/egl/libEGL_adreno200.so
05-29 22:37:39.222: D/libEGL(26806): loaded /system/lib/egl/libGLESv1_CM_adreno200.so
05-29 22:37:39.322: D/libEGL(26806): loaded /system/lib/egl/libGLESv2_adreno200.so
05-29 22:37:39.362: I/Adreno200-EGL(26806): <qeglDrvAPI_eglInitialize:299>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_JB_REL_2.0.3.1_RB1.04.01.01.45.000_msm8625_JB_REL_2.0.3.1_Merge_release_AU (Merge)
05-29 22:37:39.362: I/Adreno200-EGL(26806): Build Date: 03/28/13 Thu
05-29 22:37:39.362: I/Adreno200-EGL(26806): Local Branch:
05-29 22:37:39.362: I/Adreno200-EGL(26806): Remote Branch: m/jb_rel_2.0.3.1
05-29 22:37:39.362: I/Adreno200-EGL(26806): Local Patches: NONE
05-29 22:37:39.362: I/Adreno200-EGL(26806): Reconstruct Branch: NOTHING
05-29 22:37:39.452: D/OpenGLRenderer(26806): Enabling debug mode 0
05-29 22:37:43.822: D/AndroidRuntime(26806): Shutting down VM
05-29 22:37:43.822: W/dalvikvm(26806): threadid=1: thread exiting with uncaught exception (group=0x40fd4438)
05-29 22:37:44.022: E/AndroidRuntime(26806): FATAL EXCEPTION: main
05-29 22:37:44.022: E/AndroidRuntime(26806): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.createdialog/com.example.createdialog.NewDialog}: java.lang.ClassCastException: com.example.createdialog.NewDialog cannot be cast to android.app.Activity
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2038)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2139)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.access$700(ActivityThread.java:143)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1241)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.os.Handler.dispatchMessage(Handler.java:99)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.os.Looper.loop(Looper.java:137)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.main(ActivityThread.java:4963)
05-29 22:37:44.022: E/AndroidRuntime(26806): at java.lang.reflect.Method.invokeNative(Native Method)
05-29 22:37:44.022: E/AndroidRuntime(26806): at java.lang.reflect.Method.invoke(Method.java:511)
05-29 22:37:44.022: E/AndroidRuntime(26806): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
05-29 22:37:44.022: E/AndroidRuntime(26806): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
05-29 22:37:44.022: E/AndroidRuntime(26806): at dalvik.system.NativeStart.main(Native Method)
05-29 22:37:44.022: E/AndroidRuntime(26806): Caused by: java.lang.ClassCastException: com.example.createdialog.NewDialog cannot be cast to android.app.Activity
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.Instrumentation.newActivity(Instrumentation.java:1068)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2029)
05-29 22:37:44.022: E/AndroidRuntime(26806): ... 11 more

I might be wrong here, but as far as I know, you can't start an Intent passing a DialogFragment, you should pass an Activity. Here's what's wrong:
Intent intent = new Intent(MainActivity.this, NewDialog.class);
startActivity(intent);
Since NewDialog is declared as a DialogFragment and not as an Activity subclass.
If what you are trying to do is show the dialog, then you should do:
NewDialog dialog = NewDialog();
// use getSupportFragmentManager() if using support fragments instead of native fragments, or
// use getChildFragmentManager() if this code is inside a fragment rather than an activity
dialog.show(getFragmentManager(), "pass-any-string-here");

Without a logcat stacktrace to look at, I am assuming that your issue has to do with variable scope (here is an example explanation on the topic).
What you need to do is declare your button as a class level variable because right now it is a method variable and as such ceases to exist once your onCreate method has finished executing.
public class MainActivity extends FragmentActivity {
private Button myButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myButton = (Button) findViewById(R.id.button1);
myButton.setOnClickListener(...);
...
}
}

Activity closes when trying to asyncronously connect to twitter

I have been trying to program a twitter client for Android (using twitter4j). So far the idea is to have a simple GUI, and if there is not a file with the OAuth token in the SD Card, connect to the Twitter API using AsyncTask, get the URL for the authorization and open the default browser. However, the browser never runs. Depending on the different modifications I have made trying to fix this, either the Activity starts normally but the browser never starts or the Activity crashes. I have come to a point of a a little of frustation and confussion. Can someone point out what's wrong with my code?
public class StatusActivity extends Activity {
private static final String TAG = "StatusActivity";
EditText editText;
Button updateButton;
File oauthfile = null;
public Context context = getApplicationContext();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_status);
Log.d(TAG, "started");
// Find views
editText = (EditText) findViewById(R.id.editText); //
updateButton = (Button) findViewById(R.id.buttonUpdate);
oauthfile = new File("sdcard/auth_file.txt");
//Check if the file with the keys exist
if (oauthfile.exists()==false){
Log.d(TAG, "file not created");
Context context = getApplicationContext();
Toast toast = Toast.makeText(context, "file not created.", Toast.LENGTH_SHORT);
toast.show();
new Authorization(context).execute();
}
}
public void openBrowser (View v){
Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.google.com"));
startActivity(browserIntent);
Log.d(TAG, "onclick");
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.status, menu);
return true;
}
}
class Authorization extends AsyncTask <String, Integer, String>{
String url = null;
private Context context;
Authorization(Context context) {
this.context = context.getApplicationContext();
}
public void onPreExecute() {
super.onPreExecute();
Toast.makeText(context, "Invoke onPreExecute()", Toast.LENGTH_SHORT).show();
}
#Override
public String doInBackground(String... params) {
ConfigurationBuilder configBuilder = new ConfigurationBuilder();
configBuilder.setDebugEnabled(true)
//I have eliminated the keys from the question :)
.setOAuthConsumerKey("XXXXXXXXXXXXXX")
.setOAuthConsumerSecret("XXXXXXXXXXXXXXX");
Twitter OAuthTwitter = new TwitterFactory(configBuilder.build()).getInstance();
RequestToken requestToken = null;
AccessToken accessToken = null;
do{
try {
requestToken = OAuthTwitter.getOAuthRequestToken();
url = requestToken.getAuthorizationURL();
}
catch (TwitterException ex) {
ex.printStackTrace();
}
}
while (accessToken==null);
return url;
}
protected void onPostExecute(String result) {
super.onPostExecute(result);
Toast.makeText(context, "Opening browser.", Toast.LENGTH_SHORT).show();
Intent browserIntent = new Intent(Intent.ACTION_ALL_APPS, Uri.parse(url));
context.startActivity(browserIntent);
}
}
I know that at least checks if the file for the tokens exists because the toast "file not created" appears, and that the activity is able to run the browser if I press the button. The app has permissions to write in the SD card and use the Internet. Thanks in advance.
Logcat Trace:
03-28 19:02:32.816: E/AndroidRuntime(278): FATAL EXCEPTION: main
03-28 19:02:32.816: E/AndroidRuntime(278): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.versec.pardinus/com.versec.pardinus.StatusActivity}: java.lang.NullPointerException
03-28 19:02:32.816: E/AndroidRuntime(278): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)
03-28 19:02:32.816: E/AndroidRuntime(278): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
03-28 19:02:32.816: E/AndroidRuntime(278): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
03-28 19:02:32.816: E/AndroidRuntime(278): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
03-28 19:02:32.816: E/AndroidRuntime(278): at android.os.Handler.dispatchMessage(Handler.java:99)
03-28 19:02:32.816: E/AndroidRuntime(278): at android.os.Looper.loop(Looper.java:123)
03-28 19:02:32.816: E/AndroidRuntime(278): at android.app.ActivityThread.main(ActivityThread.java:4627)
03-28 19:02:32.816: E/AndroidRuntime(278): at java.lang.reflect.Method.invokeNative(Native Method)
03-28 19:02:32.816: E/AndroidRuntime(278): at java.lang.reflect.Method.invoke(Method.java:521)
03-28 19:02:32.816: E/AndroidRuntime(278): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
03-28 19:02:32.816: E/AndroidRuntime(278): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
03-28 19:02:32.816: E/AndroidRuntime(278): at dalvik.system.NativeStart.main(Native Method)
03-28 19:02:32.816: E/AndroidRuntime(278): Caused by: java.lang.NullPointerException
03-28 19:02:32.816: E/AndroidRuntime(278): at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:100)
03-28 19:02:32.816: E/AndroidRuntime(278): at com.versec.pardinus.StatusActivity.<init>(StatusActivity.java:30)
03-28 19:02:32.816: E/AndroidRuntime(278): at java.lang.Class.newInstanceImpl(Native Method)
03-28 19:02:32.816: E/AndroidRuntime(278): at java.lang.Class.newInstance(Class.java:1429)
03-28 19:02:32.816: E/AndroidRuntime(278): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
03-28 19:02:32.816: E/AndroidRuntime(278): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577)
03-28 19:02:32.816: E/AndroidRuntime(278): ... 11 more

This is what is causing your crash.
public Context context = getApplicationContext();
You're not even using it when you need it, so you can just get rid of this line.
Btw, something else I noticed while looking at your code is this:
oauthfile = new File("sdcard/auth_file.txt");
Don't take the "sdcard/" path for granted. Use this instead:
File dir = Environment.getExternalStorageDirectory();
File oauthfile = new File(dir, "auth_file.txt");