Android cannot access textView component from activity

Android cannot access textView component from activity - android

I have the following actvity.
package org.dewsworld.ui;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
public class DetailList extends Activity {
TextView title = (TextView) findViewById(R.id.title) ;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.detail_list);
title.setText("hello world");
}
}
Which manipulate detail_list.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent" android:weightSum="1">
<TextView android:id="#+id/title" android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_height="wrap_content" android:layout_width="match_parent"
android:text="#string/headline" />
<ListView android:id="#+id/listView1" android:layout_width="match_parent" android:layout_height="match_parent"></ListView>
</LinearLayout>
But, when I run this, I get a runtime error. LogCat is,

try like this
public class DetailList extends Activity {
TextView title;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.detail_list);
title = (TextView) findViewById(R.id.title) ;
title.setText("hello world");
}
}

package org.dewsworld.ui;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
public class DetailList extends Activity {
TextView title;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.detail_list);
title = (TextView) findViewById(R.id.title) ;;
title.setText("hello world");
}
}
its complaining because you are trying to get the value of textView using an Activity method which is not been created yet (Since its Oncreate() is yet to run)

Related

Android: Implementing Slideshow

I am trying to implement a slideshow in my android app. I have an imageview and a text view in my xml file. I want that imageview to show a slideshow of some images. The images are stored in drawable-hdpi. When I am opening this page, only text view is showing up and not the slideshow. Not a single image is showing.
Following is the java file for the same.
package abc.xys;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;
import android.widget.TextView;
public class Wishes extends Activity {
ImageView slide;
TextView msg;
int i=0;
int imgid[]={R.drawable.friends01,R.drawable.friends02,R.drawable.friends03,R.drawable.friends04,R.drawable.friends05};
RefreshHandler refreshHandler=new RefreshHandler();
#SuppressLint("HandlerLeak")
class RefreshHandler extends Handler{
#Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
Wishes.this.updateUI();
}
public void sleep(long delayMillis){
this.removeMessages(0);
sendMessageDelayed(obtainMessage(0), delayMillis);
}
};
public void updateUI(){
int currentInt=Integer.parseInt((String)msg.getText())+10;
if(currentInt<=100){
refreshHandler.sleep(2000);
msg.setText(String.valueOf(currentInt));
if(i<imgid.length){
slide.setImageResource(imgid[i]);
// slide.setPadding(left, top, right, bottom);
i++;
}
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.wishes_template);
slide = (ImageView) findViewById(R.id.slideshow);
msg = (TextView) findViewById(R.id.message);
}
}
The xml file (wishes_template) is:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:id="#+id/slideshow_layout"
>
<ImageView android:id="#+id/slideshow"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:paddingTop="20dp"
></ImageView>
<TextView android:text="10"
android:id="#+id/message"
android:layout_width="fill_parent"
android:layout_height="wrap_content"></TextView>
</LinearLayout>
Thanks in advance!

New Java class doesn't work. What am I doing wrong?

I just wanted to click on a button to see a text. Do I Need to import the public boolean onCreateOptionsMenu(Menu menu)? Or what am I doing wrong? I tried to Import some things, but it didn't help. Java-Code:
package com.example.tsd453;
import android.app.Activity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class Blume extends Activity implements OnClickListener {
public Button btn;
public TextView tw;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.blume);
btn = (Button)findViewById(R.id.BtnKlick);
tw = (TextView)findViewById(R.id.Text);
btn.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
tw.setText("Hallo");
XML:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView
android:id="#+id/Text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginRight="70dp"
android:layout_marginTop="50dp"
android:textSize="70sp" />
<Button
android:id="#+id/BtnKlick"
android:layout_width="100dp"
android:layout_height="70dp"
android:layout_centerInParent="true"
android:layout_marginTop="31dp"
android:text="Button" />
</RelativeLayout>

you could try this:
instead of
btn.setOnClickListener(this);
and
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
tw.setText("Hallo");
try this in your onCreate:
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
tw.setText("Hallo, Welt!");
}
});
and you don't need to "implements onClickListener" in class blume
and e.g. use android:layout_below="#id/tw" in the xml file of the button to set the button below the textview
EDIT:
i just tried it on my nexus 5, and this code (i think it is the same like yours) is working
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity implements OnClickListener {
public Button btn;
public TextView tw;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn = (Button)findViewById(R.id.BtnKlick);
tw = (TextView)findViewById(R.id.Text);
btn.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
tw.setText("Hallo");
}
}
i removed the options menu, but it also worked with it.
screenshot:
https://copy.com/3TX47IAK9gya
screenshot of the code in android studio:
https://copy.com/hbwnH0vZkzMn

It seems that the Button is hiding the TextView, try setting margin like:
<TextView
android:layout_marginTop="50dp" />
<Button
android:layout_marginTop="150dp"
/>
and remove center align (at least for one of them).

Fragment in layout

I'am trying to communicate betwen two fragment extended classes with the help of MainActivity bt always get an error{03-01 14:30:42.675: E/AndroidRuntime(1724): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myfrag/com.example.myfrag.Tool}: android.view.InflateException: Binary XML file line #8: Error inflating class fragment}
package com.example.myfrag;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
public class ToolBoxFrag extends FragmentActivity implements OnSeekBarChangeListener {
private static int seekvalue = 10;
private static EditText edittext;
ToolbarListener activityCallback;
public interface ToolbarListener {
public void onButtonClick(int position, String text);
}
public void onAttach(Fragment activity) {
super.onAttachFragment(activity);
try {
activityCallback = (ToolbarListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement ToolbarListener");
}
}
#Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
seekvalue = progress;
}
#Override
public void onStartTrackingTouch(SeekBar arg0) {
// TODO Auto-generated method stub
}
#Override
public void onStopTrackingTouch(SeekBar arg0) {
// TODO Auto-generated method stub
}
#Override
protected void onCreate(Bundle arg0) {
// TODO Auto-generated method stub
super.onCreate(arg0);
setContentView(R.layout.activity_main);
edittext = (EditText)findViewById(R.id.editText1);
final SeekBar seekbar =
(SeekBar) findViewById(R.id.seekBar1);
seekbar.setOnSeekBarChangeListener(this);
final Button button =
(Button) findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
buttonClicked(v);
}
});
return ;
}
public void buttonClicked (View view) {
activityCallback.onButtonClick(seekvalue,
edittext.getText().toString());
}
}
TextFragment.java
package com.example.myfrag;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class TextFragment extends FragmentActivity {
private static TextView textview;
#Override
public void onCreate( Bundle savedInstanceState) {
setContentView(R.layout.main);
textview = (TextView) findViewById(R.id.textView1);
return;
}
public void changeTextProperties(int fontsize, String text)
{
textview.setTextSize(fontsize);
textview.setText(text);
}
}
MainActivity
package com.example.myfrag;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
public class Tool extends FragmentActivity implements ToolBoxFrag.ToolbarListener {
//public TextFragment tf;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.frag2);
}
public void onButtonClick(int fontsize, String text) {
TextFragment tf = new TextFragment();
getSupportFragmentManager().findFragmentById(R.id.main);
tf.changeTextProperties(fontsize, text);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main,
menu);
return true;
}
}
xml layout
<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context=".FragmentExampleActivity" >
<fragment
android:id="#+id/activity_main"
android:name="com.example.fragmentexample.ToolbarFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
tools:layout="#layout/activity_main" />
<fragment
android:id="#+id/main"
android:name="com.example.fragmentexample.TextFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
tools:layout="#layout/main" />
</RelativeLayout>

Problem is the class path you have described the fragment name path wrong ..
it should be com.example.myfrag not com.example.fragmentexample
<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context=".FragmentExampleActivity" >
<fragment
android:id="#+id/activity_main"
android:name="com.example.myfrag.ToolbarFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
tools:layout="#layout/activity_main" />
<fragment
android:id="#+id/main"
android:name="com.example.myfrag.TextFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
tools:layout="#layout/main" />
</RelativeLayout>

Using few ListView's in one activity and layout

I'm trying to organize data recieved by SMS messages in specified ListView's.
I tried to create and activity which will contain 3 ListView's in one layout.
But, while running the activity it crashes.
Can someone help with this?
Here is the XML code:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<ListView
android:id="#+id/idList"
android:layout_width="112dp"
android:layout_height="384dp"
android:layout_gravity="center" >
</ListView>
<ListView
android:id="#+id/namesList"
android:layout_width="96dp"
android:layout_height="387dp"
android:layout_gravity="center" >
</ListView>
<ListView
android:id="#+id/phonesList"
android:layout_width="wrap_content"
android:layout_height="382dp"
android:layout_gravity="center" >
</ListView>
</LinearLayout>
And here is the activity code:
import java.util.ArrayList;
import android.app.Activity;
import android.app.ListActivity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.SmsMessage;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class DataLists extends ListActivity implements OnClickListener {
ListView idList, namesList, phonesList;
MyReciever mr;
ArrayList<String>ids= new ArrayList<String>();
ArrayList<String>names=new ArrayList<String>();
ArrayList<String>phones=new ArrayList<String>();
ArrayAdapter<String> idAdapter, namesAdapter, phonesAdapter;
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// TODO Auto-generated method stub
return super.onCreateOptionsMenu(menu);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.details_lists);
idList=(ListView)findViewById(R.id.idList);
namesList=(ListView)findViewById(R.id.namesList);
phonesList=(ListView)findViewById(R.id.phonesList);
idAdapter=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,ids );
idList.setAdapter(idAdapter);
namesAdapter= new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, names);
namesList.setAdapter(namesAdapter);
phonesAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, phones);
phonesList.setAdapter(phonesAdapter);
}
public void addItemToIdList(String st)
{
ids.add(st);
idAdapter.notifyDataSetChanged();
}
public void addItemToNamesList(String st)
{
names.add(st);
namesAdapter.notifyDataSetChanged();
}
public void addItemToPhonesList(String st)
{
phones.add(st);
phonesAdapter.notifyDataSetChanged();
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
private class MyReciever extends BroadcastReceiver{
#Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
Bundle bundle=intent.getExtras();
SmsMessage[]msgs=null;
if(bundle!=null)
{
Object[]pdus=(Object[]) bundle.get("pdus");
msgs=new SmsMessage[pdus.length];
for(int i=0;i<msgs.length;i++)
{
int index=0, prev=0;
String msgBody=msgs[i].getMessageBody().toString();
index=msgBody.indexOf(';');
prev=index;
String name=msgBody.substring(0, index);
addItemToNamesList(name);
msgBody=msgBody.substring(index+1);
index=msgBody.indexOf(';');
String id=msgBody.substring(prev, index);
addItemToIdList(id);
msgBody=msgBody.substring(index+1);
String phone=msgBody;
addItemToPhonesList(phone);
}
}
}
}
}

You have extended ListActivity. This is a convenience class that can be used to display a single ListView. The crash is clearly described in your logcat/stacktrace:
java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
Since your layout contains 3 ListViews, you probably can't use ListActivity anyway. Just change your activity to extend Activity and go from there.

intent not working when swiching from one activity to another

I have made a simple android program with two activities,in that 1st activity contains an edittext and a button,and second activity contain a textview.Now when the button in 1st activity pressed the text from Edittext should go to 2nd activity's textView.I have tried code as below,but it's not working:
MainActivity.java
package com.example.myweb;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.myweb";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b =(Button)findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
EditText ed = (EditText)findViewById(R.id.edit_msg);
Intent i = new Intent(getApplicationContext(),Act2.class);
String s= ed.getText().toString();
i.putExtra("EXTRA_MESSAGE", s);
startActivity(i);
}
});
}
}
Act2.java
package com.example.myweb;
import org.w3c.dom.Text;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Act2 extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act2);
Button b1=(Button)findViewById(R.id.button1);
b1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
TextView tv = (TextView)findViewById(R.id.tv1);
Intent i =getIntent();
String msg = i.getStringExtra(MainActivity.EXTRA_MESSAGE);
tv.setText(msg);
setContentView(tv);
}
});
}
}
please help me.thank you

Just try this:
In MainActivity.java:
declare Button b and EditText ed as a class field (i.e. keep it outside onCreate())
class MainActivity.java
{
Button b;
EditText ed;
...
onCreate() {
...
b =(Button)findViewById(R.id.button1);
ed = (EditText)findViewById(R.id.edit_msg);
b.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent i = new Intent(MainActivity.this,Act2.class);
String s= ed.getText().toString();
i.putExtra("EXTRA_MESSAGE", s);
startActivity(i);
}
});
...
In Act2.java:
...
Intent i = getIntent();
String msg = i.getStringExtra("EXTRA_MESSAGE");
TextView tv = (TextView)findViewById(R.id.tv1);
tv.setText(msg);
Button b1=(Button)findViewById(R.id.button1);
b1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
...

You are using
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
So, in MainActivity
i.putExtra(EXTRA_MESSAGE, s);
startActivity(i);
(OR)
String message = intent.getStringExtra("EXTRA_MESSAGE");
also,
i.putExtra("EXTRA_MESSAGE", s);

Change
String msg = i.getStringExtra(MainActivity.EXTRA_MESSAGE);
to
String msg = i.getStringExtra("EXTRA_MESSAGE");
MainActivity.EXTRA_MESSAGE would mean a static variable of MainActivity.java class. Hope you get the difference. You need the variable EXTRA_MESSAGE which you had put in intent i
Edit: For your crash, we need a logcat o/p and activity, manifest code. But possible reasons:
Activity Act2.java is not declared in manifest file.
You said you have only a textview in second activity. But you are trying to get button1 from act2.xml. So you are getting Force close.
Change Act2.java 's onCreate() as
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act2);
TextView tv = (TextView)findViewById(R.id.tv1);
Intent i =getIntent();
String msg = i.getStringExtra("EXTRA_MESSAGE");
tv.setText(msg);
}
You don't need to call setContentView(tv); as it is already there in act2.xml and you are using setContentView(R.layout.act2);
Hope your problem gets solved.

Use this code
**MainActivity.java**
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = (Button)findViewById(R.id.button1);
final EditText editText = (EditText)findViewById(R.id.editText1);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent(getApplicationContext(), SecondActivity.class);
intent.putExtra("EXTRA_MESSAGE", editText.getText().toString());
startActivity(intent);
}
});
}
}
**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" >
<EditText
android:id="#+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="74dp"
android:layout_marginTop="26dp"
android:ems="10" >
<requestFocus />
</EditText>
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="#+id/editText1"
android:layout_marginLeft="69dp"
android:layout_marginTop="47dp"
android:text="Button" />
</RelativeLayout>
**SecondActivity.java**
public class SecondActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// TODO Auto-generated method stub
setContentView(R.layout.second);
Intent intent = getIntent();
final String message = intent.getStringExtra("EXTRA_MESSAGE");
Button button = (Button)findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
TextView textView = new TextView(SecondActivity.this);
textView.setText(message);
setContentView(textView);
}
});
}
}
**second.xml**
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.tester"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="8" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.tester.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=".SecondActivity"></activity>
</application>
</manifest>

Try
Intent i = new Intent(MainActivity.this,Act2.class);

You are using
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
So, in MainActivity
i.putExtra(EXTRA_MESSAGE, s);
startActivity(i);

please review and change your code its works
package com.example.activityact;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b =(Button)findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
EditText ed = (EditText)findViewById(R.id.editText1);
Intent i = new Intent(getApplicationContext(),Act2.class);
String s= ed.getText().toString();
i.putExtra("EXTRA_MESSAGE", s);
startActivity(i);
}
});
}
}
Act2.java
package com.example.activityact;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
public class Act2 extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act2);
// TODO Auto-generated method stub
TextView tv = (TextView) findViewById(R.id.textView1);
Intent i =getIntent();
// String msg = i.getStringExtra(EXTRA_MESSAGE);
//String receiver = getIntent().getStringExtra(EXTRA_MESSAGE);
String message = i.getStringExtra("EXTRA_MESSAGE");
tv.setText(message);
}
}

Value of the EXTRA_MESSAGE variable in MainActivity.java is different then the key value that you are putting message in to intent.
MainActivity.java:
public final static String EXTRA_MESSAGE = "com.example.myweb";
i.put("EXTRA_MESSAGE",s);
Act2.java: (you are accessing by extra_message variable which is not correct)
Intent i = getIntent();
String text = i.getStringExtra(MainActivity.EXTRA_MESSAGE); //WHICH IS DIFFER FROM THE KEY VALUE
So key value should be the same at the time of setting and getting the value. here while setting the value key is "EXTRA_MESSAGE" and while getting "com.example.myweb" so you will get null pointer exception.
SOLUTION:
just change the line in Act2.java
Intent i = getIntent();
String text = i.getStringExtra("EXTRA_MESSAGE");
Also check your menifest file for the activities declaration.
Hope it may help you.

Did you remember to correctly define your second activity in the manifest XML?
Check out this great guide for anything else you might have missed: http://developer.android.com/training/basics/firstapp/starting-activity.html

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