Develop Reference

apk giving error " unfortunately Helloapp1 stopped "

Whenever i try to make any app even simple hello world app every time i get this type of error, even in android virtual devices and android phone also, so i want to know that what are mistakes that i made every time in made, and can any one please make this code correct. So that i can run this app on my mobile phone.
this is my MainActivity_hello.java file
package com.example.helloapp1;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity_hello extends Activity {
TextView tb;
Button b;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_activity_hello);
addListenerOnButton();
tb= (TextView) findViewById(R.id.Tbox);
}
private void addListenerOnButton() {
// TODO Auto-generated method stub
b = (Button)findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener()
{
public void onClick(View arg0)
{
tb.setText( String.format( " Hi ") );
}
});
}
#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_activity_hello, menu);
return true;
}
}
activity_main_activity_hello.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/button1"
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=".MainActivity_hello" >
<TextView
android:id="#+id/Tbox"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/Tbox"
android:layout_centerHorizontal="true"
android:layout_marginTop="44dp"
android:text="Hit Me" />
</RelativeLayout>
Androidmanifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.helloapp1"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.helloapp1.MainActivity_hello"
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>

There could be many reasons, You have to be sure that:
The R. import is not R.android, which references to the Android System Resources. If it is, Your Button b is referred to the system framework button. This System Framework Button is identified with "button1".
Well, in Your case, I think You have the wright import, because You have no problem by using the id for the textView.
You gave Your RelativeLayout the same Id like the button:
android:id="#+id/button1"
The best way would be, give both another, different id.
I don´t know why You are using String.format(), just use tb.setText("Hi");

You are declaring the same id button1 twice, once in the layout and once for the button.
Change it to something else for your layout, like:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/holder1"
...
>
Since it seems like you are getting started with Android development I would recommend switching over to using Android Studio.

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.

Helloworld Doesn't run on Emulator

Okay, this is really ticking me off. I ran it on both my emulator and on an android device. The code does NOT display "Helloworld, Android -mykong.com". I start the app, find it on the emulator, click on it, and it goes to interface of the app. However, it is just a blank screen! This error is not an issue of me finding the app, its not with the emulator or the android phone, the issue has to lie either in the code or in the way the code is structured/built. I know the the helloworld code is 100% correct because its from a reputable tutorial site. These are my three pairs of code. Please help, I am in desperate need!
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.test123"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.test123.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>
MainActivity.java
package com.example.test123;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void activity()
{
Intent helloWorld = new Intent(getApplicationContext(), HelloWorldjavaactivity.class );
startActivity( helloWorld );
}
#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;
}
}
HelloWorldjavaactivity.java
package com.example.test123;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class HelloWorldjavaactivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
TextView text = new TextView(this);
text.setText("Hello World, Android - mkyong.com");
setContentView(text);
}
}
Activity_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=".MainActivity" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="35dp"
android:layout_marginTop="57dp"
android:text=""
/>
</RelativeLayout>

You're not starting the HelloWorldjavaactivity.java activity. You need something like the following in your MainActivity:
Intent helloWorld = new Intent(getApplicationContext(), HelloWorldjavaactivity.class );
startActivity( helloWorld );
Of course, you need that code to be triggered by some even, a button press for example.
It would be easier to just eliminate the second activity (since your MainActivity isn't doing anything anyway) and put the code in your MainActivity instead. You'll also need to edit the layout for your MainActivity so that it includes the appropriate views.

developer.android.com My First Android App | Stopped Error

i tried to run my first android application but i could not execute it. i followed instructions step by step from developer.android.com . I used only Copy and Paste for codes. But when i try to run my app AVD is giving error "Unfortunately, My First App has stooped."
Screen Captures are here :
AVD Settings : Click
LOG FILE:Click
AndroidManifest.xml
<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="15" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/title_activity_main" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".DisplayMessageActivity"
android:label="#string/title_activity_display_message" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.myfirstapp.MainActivity" />
</activity>
</application>
</manifest>
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<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>
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" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="#string/hello_world"
tools:context=".DisplayMessageActivity" />
</RelativeLayout>
strings.xml
<resources>
<string name="app_name">My First App</string>
<string name="menu_settings">Settings</string>
<string name="title_activity_main">MainActivity</string>
<string name="edit_message">Bir şeyler yaz</string>
<string name="button_send">Send</string>
<string name="hello_world">Hello world!</string>
<string name="title_activity_display_message">My Message</string>
</resources>
DisplayMessageActivity.java
package com.example.myfirstapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.*;
public class DisplayMessageActivity extends Activity {
#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);
}
}
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.*;
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
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);
}
}

typo mistake in Button click method,s is not small its capital in xml layout file...
public void SendMessage(View view) {
^

Opening a new Activity when clicking a menu item button is not working

So I have 2 activities and in the first one I have a menu item that once clicked should open the second activity. The changing part works but it's not changing what it is supposed to, in the second activity which I activate with this :
Intent intent = new Intent(this, EditView.class);
startActivity(intent);
break;
in the first activity onOptionsItemSelected, and I click a button from the menu, in this second activity I have a diferent layout and I do this setContentView(R.layout.second); to change the layout I have a functional xml file because I tried it in another project, in the manifest file I have this :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="ro.merca.ionel"
android:versionCode="1"
android:versionName="1.0" >
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-sdk android:minSdkVersion="15" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name" >
<activity
android:name=".FileList"
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=".EditView"
android:label="#string/app_name" />
</application>
</manifest>
the problem is that when I click the option from the menu it loads a simple layout without all the things I put in second.xml... I don't know that the problem is...
public class EditView extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second);
Intent intent = getIntent();
TextView tv = new TextView(this);
final TextView name = (TextView) findViewById(R.id.name);
final TextView text = (TextView) findViewById(R.id.text);
setContentView(tv);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
menu.add(1,1,1,"Salveaza Nota").setIcon(android.R.drawable.btn_default);
menu.add(1,2,2,"Anuleaza Modificari").setIcon(android.R.drawable.btn_default);
menu.add(1,3,3,"Sterge Nota").setIcon(android.R.drawable.btn_default);
menu.add(1,4,4,"Share").setIcon(android.R.drawable.btn_default);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()){
case 1 :
Intent intent = new Intent(this, EditView.class);
this.startActivity(intent);
break;
case 2 :
break;
case 3 :
break;
case 4 :
break;
default:
break;
}
return super.onOptionsItemSelected(item);
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Nume" />
<EditText
android:id="#+id/name"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Text" />
<EditText
android:id = "#+id/text"
android:inputType="text|textMultiLine"
android:minLines="5"
android:gravity="top"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>

You are calling setContentView twice in onCreate(). Remove the second one and try again.

I am bit confused over here. If you are just moving from 1st activity to 2nd without passing any values then what's the use of using getIntent() etc?
Write simply this much, and you will land on your desired activity:
public class EditView extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second);
TextView tv = new TextView(this);
final TextView name = (TextView) findViewById(R.id.name);
final TextView text = (TextView) findViewById(R.id.text);
}
}