Develop Reference

Android Studio: SearchView: error in searchView.setSearchableInfo(searchManager.getSearchableInfo(cn));

I'm a newbie working on an android app, following is the first screen of the app. I want my application to perform search using that search dialog box.
For this, I followed http://developer.android.com/guide/topics/search/search-dialog.html
But I was getting following error:
Logcat:
FATAL EXCEPTION: main
Process: com.example.shalini.circlelayout, PID: 19330
java.lang.NullPointerException
at com.example.shalini.circlelayout.MainActivity.onCreateOptionsMenu(MainActivity.java:69)
where line:69 in MainActivity.java is:
ComponentName cn = new ComponentName(this, SearchResultsActivity.class);
searchView.setSearchableInfo(searchManager.getSearchableInfo(cn));
I referred to this
Cannot get searchview in actionbar to work
and made changes but the same problem still persists. My question is why is it showing error in searchView.setSearchableInfo(searchManager.getSearchableInfo(cn)); line. I couldn't figure that out, I still think that error is arising due to some other part of the code, maybe searchresultsactivity.xml or SearchResultsActivity.java. Any help is much appreciated. Thank you.
Code below:
MainActivity.java
package com.example.shalini.circlelayout;
import android.app.SearchManager;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.SearchView;
import android.support.v7.widget.Toolbar;
import android.view.MenuInflater;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;
import android.widget.ImageButton;
public class MainActivity extends AppCompatActivity {
EditText e1;
ImageButton imageButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
e1 = (EditText) findViewById(R.id.search);
addListenerOnButton();
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
private void addListenerOnButton() {
imageButton = (ImageButton) findViewById(R.id.imageButton);
imageButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(getApplicationContext(), SymptomsList.class);
startActivity(i);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
// Associate searchable configuration with the SearchView
SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
SearchView searchView = (SearchView) menu.findItem(R.id.search).getActionView();
ComponentName cn = new ComponentName(this, SearchResultsActivity.class);
searchView.setSearchableInfo(searchManager.getSearchableInfo(cn));
//call to getSearchableInfo()
//SearchableInfo object
//SearchView starts an activity with the ACTION_SEARCH intent when a user submits a query
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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
SearchResultsActivity.java
package com.example.shalini.circlelayout;
import android.app.ListActivity;
import android.app.SearchManager;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
public class SearchResultsActivity extends ListActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
handleIntent(getIntent());
}
#Override
public void onNewIntent(Intent intent) {
super.onNewIntent(intent);
handleIntent(intent);
}
private void handleIntent(Intent intent) {
if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
String query = intent.getStringExtra(SearchManager.QUERY);
doMySearch(query);
//use the query to search your data somehow
}
}
private void doMySearch(String query) {
Log.d("Event", query);
}
}
content_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent"
android:layout_height="wrap_content" android:padding="#dimen/activity_horizontal_margin"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:showIn="#layout/activity_main" tools:context=".MainActivity"
android:background="#drawable/blue_bluecrop1">
<EditText
android:layout_width="160dp"
android:layout_height="60dp"
android:id="#+id/search"
android:inputType="text"
android:hint="#string/sym"
android:drawableStart="#drawable/search_s2"
android:drawableLeft="#drawable/search_s2"
android:padding="20dp"
android:gravity="center_vertical|center_horizontal"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_marginLeft="5dp"
android:layout_marginRight="5dp"
android:layout_marginTop="5dp"
android:ellipsize="end"
android:background="#drawable/roundededittext"/>
<ImageButton
android:layout_width="40dp"
android:layout_height="45dp"
android:contentDescription="#string/symbutton"
android:id="#+id/imageButton"
android:background="#00000000"
android:layout_marginLeft="160dp"
android:layout_marginStart="160dp"
android:layout_marginTop="270dp"
android:clickable="true"
/>
searchresultsactivity.xml
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
#xml/searchable
<?xml version="1.0" encoding="utf-8"?>
<searchable xmlns:android="http://schemas.android.com/apk/res/android"
android:label="#string/app_name"
android:hint="#string/search_searchable">
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.shalini.circlelayout" >
<application
android:allowBackup="true"
android:fullBackupContent="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name"
android:theme="#style/AppTheme.NoActionBar" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<action android:name="android.intent.action.VIEW" />
<category android:name="android.intent.category.BROWSABLE" />
<data android:scheme="http"
android:host="www.example.com"
android:pathPrefix="/doraemon" />
</intent-filter>
<meta-data
android:name="android.app.default_searchable"
android:value=".SearchResultsActivity" />
</activity>
<activity android:name=".SearchResultsActivity">
<intent-filter>
<action android:name="android.intent.action.SEARCH" />
</intent-filter>
<meta-data android:name="android.app.searchable"
android:resource="#xml/searchable" />
</activity>
</application>

Your searchView seems to be null. How did you make it?

Cannot cast 'android.view.View' to 'com.example.shabeer.listview.ListView'

I get an error in this line here
list_view = (ListView)findViewById(R.id.listView_id); shows error
inconvertible type; cannot cast android.view.View to
com.example.shabeer.listview.ListView
also the list_view.setAdapter(adapter); is not working.
ListView class:
package com.example.shabeer.listview;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
public class ListView extends AppCompatActivity {
public static ListView list_view;
private static String[] NAMES = new String[] { "Tom", "John", "Jack", "Pal"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_view);
}
public void listView(){
list_view = (ListView)findViewById(R.id.listView_id);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.name_list, NAMES);
list_view.setAdapter(adapter);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_list_view, 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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
activity_list_view.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:orientation="vertical"
android:paddingBottom="#dimen/activity_vertical_margin" tools:context=".ListView">
<ListView
android:id="#+id/listView_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal" />
</LinearLayout>
AndroidManifect.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.shabeer.listview" >
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".ListView"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

Change your class name "ListView" to "OtherName"
public class ListView extends AppCompatActivity {
to
public class ListViewSample extends AppCompatActivity {

You cannot cast an Android listview to your own listview.
Instead of "com.example.shabeer.listview.ListView" you need a "android.widget.ListView". This is the one you are referencing in your xml layout file.
public static android.widget.ListView list_view;
and
list_view = (android.widget.ListView)findViewById(R.id.listView_id);

Call listView() method inside onCreate then try, it should work.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_view);
listView();
}

Edit: This would be the answer if your ListView were a View, but now I see that it's actually an Activity. ListView is a very misleading name for an activity class!
Use the fully-qualified class name in your XML:
<com.example.shabeer.listview.ListView
android:id="#+id/listView_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal" />
Otherwise, it will assume you mean android.widget.ListView.

"Unfortunately application has stopped." in Android - trying to send SMSmessage

I'm beginner in Android development and I'm trying to make Android app which will send SMS to another phone when button is clicked. I don't have Android phone so I'm trying to do that via emulators. I start one emulator which will be my "phone" which send SMS and another emulator which receives SMS.
Everything is compiled well and app starts, but when I click on button, I got message that "Unfortunately, app has stopped".
Here is the code which I have made.
acitivity_main.xml
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.email.MainActivity" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="23dp"
android:layout_marginTop="44dp"
android:text="Button" />
and here is MainActivity.java
package com.example.email;
import com.example.email.R;
import android.app.Activity;
import android.os.Bundle;
import android.telephony.SmsManager;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//adding listener to the button
final Button button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
String phoneNumber = "5556";
String message = "Proba";
//sends SMS to emulator with number 5556
SmsManager sms = SmsManager.getDefault();
sms.sendTextMessage(phoneNumber, null, message, null, null);
}
});
}
//this is default function, I haven't changed anything
#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);
}
}
manifest file
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.email"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

add
<uses-permission android:name="android.permission.SEND_SMS" />
in your manifest.xml

Unable to display the full screen mode in android

Splash Screen Launcher Activity
Unable to display full screen mode in android
package com.example.wabco;
import android.support.v7.app.ActionBarActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.Window;
import android.view.WindowManager;
public class SplashScreen extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.splash_layout);
final int welcomeScreenDisplay = 3000;
/** create a thread to show splash up to splash time */
Thread welcomeThread = new Thread() {
int wait = 0;
#Override
public void run() {
try {
super.run();
/**
* use while to get the splash time. Use sleep() to increase
* the wait variable for every 100L.
*/
while (wait < welcomeScreenDisplay) {
sleep(100);
wait += 100;
}
} catch (Exception e) {
System.out.println("EXc=" + e);
} finally {
/**
* Called after splash times up. Do some action after splash
* times up. Here we moved to another main activity class
*/
startActivity(new Intent(SplashScreen.this,LoginActivity.class));
finish();
}
}
};
welcomeThread.start();
}
#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);
}
}
Login Activity
Next Activity Login Page
package com.example.wabco;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.Window;
import android.view.WindowManager;
public class LoginActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.login, 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);
}
}
splash layout
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:gravity="center"
android:background="#drawable/spalshscreen"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.wabco.SplashScreen" >
</RelativeLayout>
activity_login
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/login"
android:gravity="center"
android:orientation="horizontal"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.wabco.LoginActivity" >
<RelativeLayout
android:id="#+id/relativeLayout1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="14dp"
android:layout_marginTop="23dp" >
</RelativeLayout>
<RelativeLayout
android:id="#+id/relativeLayout2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/editText2"
android:layout_marginLeft="62dp"
android:layout_marginTop="16dp" >
</RelativeLayout>
<EditText
android:id="#+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/editText2"
android:layout_marginBottom="31dp"
android:layout_toRightOf="#+id/relativeLayout1"
android:ems="10"
android:gravity="center"
android:hint="Username"
android:inputType="textPersonName" >
<requestFocus />
</EditText>
<EditText
android:id="#+id/editText2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/button1"
android:layout_alignLeft="#+id/editText1"
android:layout_marginBottom="178dp"
android:ems="10"
android:gravity="center"
android:hint="Password"
android:inputType="textPassword" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/relativeLayout2"
android:layout_alignParentBottom="true"
android:layout_marginBottom="180dp"
android:background="#drawable/buttonlogin" />
</RelativeLayout>
Attached Screenshot of Log/Error
manifest file
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.wabco"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="21" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".SplashScreen"
android:label="#string/app_name"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".LoginActivity"
android:label="#string/title_activity_login" >
</activity>
<activity
android:name=".HomeActivity"
android:label="#string/title_activity_home" >
</activity>
</application>
</manifest>

just replace this 4 lines in splashScreen.java in OnCreate()
requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
super.onCreate(savedInstanceState);
setContentView(R.layout.splash_layout);

In your Splash Screen Launcher Activity
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.splash_layout);
After Change your Splash Screen Launcher Activity like this
import android.support.v7.app.ActionBarActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.Window;
import android.view.WindowManager;
public class SplashScreen extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.splash_layout);
final int welcomeScreenDisplay = 3000;
/** create a thread to show splash up to splash time */
Thread welcomeThread = new Thread() {
int wait = 0;
#Override
public void run() {
try {
super.run();
/**
* use while to get the splash time. Use sleep() to increase
* the wait variable for every 100L.
*/
while (wait < welcomeScreenDisplay) {
sleep(100);
wait += 100;
}
} catch (Exception e) {
System.out.println("EXc=" + e);
} finally {
/**
* Called after splash times up. Do some action after splash
* times up. Here we moved to another main activity class
*/
startActivity(new Intent(SplashScreen.this,LoginActivity.class));
finish();
}
}
};
welcomeThread.start();
}
#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);
}
}

add these line in oncreate
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
use this
<activity
android:name=".SplashScreen"
android:label="#string/app_name"
android:theme="#android:style/Theme.NoTitleBar.Fullscreen"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.DisplayMessageActivity}

I’m following the android tutorial First App in the link below:
https://developer.android.com/training/basics/firstapp/starting-activity.html
The app can be launched in the emulator but the problem is when I click on the button “send, the application crashed with the message “unfortunately, my fist app has stopped”.
I think I did follow the instructions in the tutorial and can’t figure out where is the problem from.
Logcat send this message:
02-12 16:19:36.031: E/AndroidRuntime(786): java.lang.RuntimeException:
Unable to instantiate activity
ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.DisplayMessageActivity}:
java.lang.NullPointerException
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage" />
</LinearLayout>
MAinActivity.java
package com.example.myfirstapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
/** Called when the user clicks the Send button */
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
// Do something in response to button
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#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;
}
}
activity_display_message.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".DisplayMessageActivity" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
</RelativeLayout>
DisplayMessageActivity.java
package com.example.myfirstapp;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.view.MenuItem;
import android.widget.TextView;
public class DisplayMessageActivity extends Activity {
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
#SuppressLint("NewApi")
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the message from the intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
// Make sure we're running on Honeycomb or higher to use ActionBar APIs
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
// Show the Up button in the action bar.
getActionBar().setDisplayHomeAsUpEnabled(true);
}
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
}
MyFirstApp Manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myfirstapp"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.myfirstapp.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.example.myfirstapp.DisplayMessageActivity"
android:label="#string/title_activity_display_message"
android:parentActivityName="com.example.myfirstapp.MainActivity" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.myfirstapp.MainActivity" />
</activity>
</application>
</manifest>
Thank you for your help

I believe the problem is
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
before onCreate(). Intent needs a Context which isn't available until the Activity has been created. Remove those lines since you already have it in onCreate().
Also, when it crashes, post your full logcat because it will tell us, usually, exactly where and what the problem is.