want to send text from one activity to another in android

want to send text from one activity to another in android - android

I have tried to write a program for sending text from main activity to another activity "DisplayMessageActivity". But when I have installed that app in my android mobile, after pressing the button , it crashed with a message "unfortunately app has stopped'"
My different files are as under...(eclipse)
MainActivity.java file...
package com.example.practice3;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
public class MainActivity extends ActionBarActivity {
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
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);
}
}
2.fragment_main.xml file
<?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>
DisplayMessageActivity.java file
package com.example.practice3;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class DisplayMessageActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
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);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.display_message, 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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_display_message,
container, false);
return rootView;
}
}
}
4.fragment_display_message.xml file
<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.practice3.DisplayMessageActivity$PlaceholderFragment" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
</RelativeLayout>
5.Strings.xml file
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">My First App</string>
<string name="edit_message">Enter a message</string>
<string name="button_send">Send</string>
<string name="action_settings">Settings</string>
<string name="title_activity_main">MainActivity</string>
<string name="title_activity_display_message">DisplayMessageActivity</string>
<string name="hello_world">Hello world!</string>
</resources>

In DisplayMessageActivity.java file comment out below code.
There is no R.id.container in corresponding xml file.
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}

Have you added your DisplayMessageActivity in the AndroidManifest.xml in the application tag like:
<activity android:label="#string/app_name" android:name=".DisplayMessageActivity"/>

Just check this link, if you copy the code, it will work!
I recommend you create a blank activity instead of an activity with fragment also, it's easier to start using android!
Create an intent where you are going to store the text :
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);
}
... and here is the onCreate method of the activity you just started :
#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);
}

Related

Displaying a button under a string message

Hello I am very new to android programming. I would like to get some help regarding displaying a button under a string message under an activity which has been newly activated. Hope someone can help me. Here is the code which I have for the class MyActivity which activates when the button app tutorial is pressed. The xml for my main activity is also there. Also the displaymessage activity class and xml is also there.
package com.example.sadi_ace.myfirstapp;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
public class MyActivity extends ActionBarActivity {
public final static String EXTRA_MESSAGE = "com.example.sadi_ace.myfirstapp.MESSAGE";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
}
/** Called when the user clicks the Send button */
public void TutorialText(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
String message = "This is the android tutorial, if you want to pass on the to the " +
"functions please press SKIP!";
intent.putExtra(EXTRA_MESSAGE, message);
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.menu_my, 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);
}
}
XML for main activity
<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="vertical"
android:background="#800080"
android:weightSum="1">
<Button
android:layout_width="150dp"
android:layout_height="wrap_content"
android:text="#string/button_tutorial"
android:background="#FFFFFF"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
android:onClick="TutorialText"
/>
</RelativeLayout>
DisplayMessageActivity class code
package com.example.sadi_ace.myfirstapp;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.TextView;
public class DisplayMessageActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = getIntent();
String message = intent.getStringExtra(MyActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
}
// #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_display_message, 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);
}
}
XML for DisplayMessageActivity class
<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="vertical"
android:background="#800080"
android:weightSum="1">
</RelativeLayout>

Add button in your xml file activity_my like
<Button
android:id="#+id/btnskip"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
After that use this button id in "onCreate " method and assign it to some button
Button skip;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
skip=(Button)findViewById(R.id.btnskip);
//add on click listener
skip.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent intent = new Intent(this, DisplayMessageActivity.class);
String message = "This is the android tutorial, if you want to pass on the to the " +
"functions please press SKIP!";
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
});
}

How do I start a new activity from the main activity and display all the elements along with the background?

I am a beginner in Android programming and to learn it I am making a sample calculator example myself using the references on the web, now this is something I want to do. I followed the tutorial "Building you First App" as provided on official Google documentation and I was successful in sparking off a new activity on hitting a button using the Intents class, here is the image of the application at the start -:
but when I hit the enter button, even though I have set the android:background option for the new activity it doesn't set the background to that image, the only thing I get is a blank activity, here is the image -:
here is the code for my MainActivity that starts up when the application starts -
<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="vertical"
android:background="#drawable/math_symbols" >
<Button android:id="#+id/enter_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/enter_button"
android:onClick="enterCalculator"/>
</LinearLayout>
Here's the code for the second activity that starts when I hit the enter button and this is done using Intents -:
<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="vertical"
android:background="#drawable/calculato_activity_1" >
<RadioGroup android:id="#+id/operation_radio_group"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="30dip"
android:orientation="horizontal">
<RadioButton android:id="#+id/sum"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/sum">
</RadioButton>
<RadioButton android:id="#+id/difference"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/difference">
</RadioButton>
<RadioButton android:id="#+id/multiply"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/multiply">
</RadioButton>
</RadioGroup>
</LinearLayout>
no background is displayed above and no views are added to the screen, also here is how I am using Intents in the MainActivity class -:
package com.example.mathcalculator;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
public class MainActivity extends ActionBarActivity {
// this is the message used to enter the main calculator activity
public static String ENTER_MESSAGE = "com.example.mathcalculator.MainActivity.Message";
// this method is used to enter the actual calculator screen
public void enterCalculator(View view){
// we create an Intent to carry over the data from the button and enter the CalculatorActivity1
Intent intent = new Intent(this, CalculatorActivity1.class);
// put the key-value pair into the intent
intent.putExtra(ENTER_MESSAGE, "ENTER");
// start the new activity with the intent as the input which carries over the message bundle
startActivity(intent);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
and here is the code for the CalculatorActivity1 class -:
package com.example.mathcalculator;
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
public class CalculatorActivity1 extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.calculator_activity1, 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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(
R.layout.fragment_calculator_activity1, container, false);
return rootView;
}
}
}

You need to set a content view for your activity. It is already done in the sample app activity, so inside the oncreate method of your MainActivity, you can see: setContentView(R.layout.activity_main);
It is setting the activity_main layout to the MainActivity content view.
So you need to do this to the CalculatorActivity1 too, under the super.onCreate(savedInstanceState);
You can find your second layout name in the res/layout folder.

You are not commiting the change in fragment. After the setContentView(R.layout.xml_file); inside onCreate you should have this:
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}

You missed to set background in the second activity xml.
android:background="#drawable/math_symbols"
Bind the xml layout to the second activity CalculatorActivity1:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.<xmlName>);
}

Android app stop when is being to run

I'm new to android and java. this is my first app. an example of a book. I did all steps according the book. the app is going to increase the number by click on + button
this is my Java file :
package com.example.myprayercounter;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import android.os.Build;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
int counter;
TextView tView;
Button btn;
public PlaceholderFragment() {}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
counter = 0;
tView = (TextView)getActivity().findViewById(R.id.txt_textTwo);
btn = (Button)getActivity().findViewById(R.id.btn_buttonOne);
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
counter++;
tView.setText(" " + counter);
}
});
return rootView;
}
}
}
xml file :
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#fbfbdd"
android:gravity="center_horizontal"
android:orientation="vertical"
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.myprayercounter.MainActivity$PlaceholderFragment" >
<TextView
android:id="#+id/txt_textOne"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="تعداد ذکرهای من"
android:textColor="#763f05"
android:textSize="20dp" />
<TextView
android:id="#+id/txt_textTwo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="0"
android:textColor="#763f05"
android:textSize="40dp" />
<Button
android:id="#+id/btn_buttonOne"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#763f05"
android:text="+"
android:textColor="#fbfbdd"
android:textSize="40dp" />
</LinearLayout>
I got this error at first run of the app :
What is my mistakes? and how i can fix them?
Thanks in advance

change:
tView = (TextView)getActivity().findViewById(R.id.txt_textTwo);
btn = (Button)getActivity().findViewById(R.id.btn_buttonOne);
to ( getActivity() --> rootView)
tView = (TextView)rootView.findViewById(R.id.txt_textTwo);
btn = (Button)rootView.findViewById(R.id.btn_buttonOne);
in PlaceholderFragment, your View is rootView and you need find your view from that

get null pointer error when trying to getText

I am new to Android, so please forgive my ignorance. I have tried searching the forums, but haven't been able to find anything to get this to work. I am trying to use .getText().toString() (see below), but get a java.lang.NullPointerException error. I changed my setContentView so that it would look at the fragment_main.xml, but still returns a null for my different components. The goal of this is very simple, just to change the text on the TextView, since I am just getting started. Any help would be appreciated.
package com.example.app;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
Button changeTxt = (Button) findViewById(R.id.btnChangeText);
final TextView textView = (TextView) findViewById(R.id.txtMessage);
changeTxt.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String text = textView.getText().toString();
if (text.contains("World")) {
textView.setText("Hello Android!");
}
else {
textView.setText(("Hello World!"));
}
}
});
}
public void onStart(){
super.onStart();
}
public void onResume(){
super.onResume();
}
public void onPause(){
super.onPause();
}
public void onStop(){
super.onStop();
}
public void onDestroy(){
super.onDestroy();
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
}
Here is the xml:
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Large Text"
android:id="#+id/txtMessage"
android:layout_gravity="center_horizontal" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Change Text"
android:id="#+id/btnChangeText"
android:layout_gravity="center_horizontal" />
</LinearLayout>
Fllo, updated code:
XML fragment_main.xml
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Large Text"
android:id="#+id/txtMessage1"
android:layout_gravity="center_horizontal" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Change Text"
android:id="#+id/btnChangeText1"
android:layout_gravity="center" />
</FrameLayout>
</LinearLayout>
main activity
package com.example.app;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
public void onStart(){
super.onStart();
}
public void onResume(){
super.onResume();
}
public void onPause(){
super.onPause();
}
public void onStop(){
super.onStop();
}
public void onDestroy(){
super.onDestroy();
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
Button changeTxt = (Button) findViewById(R.id.btnChangeText);
final TextView textView = (TextView) findViewById(R.id.txtMessage);
changeTxt.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view)
{
String text = textView.getText().toString();
if (text.contains("World"))
{
textView.setText("Hello Android!");
}
else
{
textView.setText(("Hello World!"));
}
}
});
return rootView;
}
}
}

The NullPointerException occurs because, it seems that you have the same layout for your Activity and your Fragment:
// Activity
setContentView(R.layout.fragment_main);
// Fragment
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
You need to check if your views (TextView & Button) are in the right layout and not into aonther (I guess activity_main).
Two solutions:
Copy/past your views inside fragment_main to activity_main and change setContentView(R.layout.activity_main).
Or let your views inside fragment_main and use the following code to find your view inside your Fragment, as follows:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
Button changeTxt = (Button) rootView.findViewById(R.id.btnChangeText);
final TextView textView = (TextView) rootView.findViewById(R.id.txtMessage);
changeTxt.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String text = textView.getText().toString();
if (text.contains("World")) {
textView.setText("Hello Android!");
}
else {
textView.setText(("Hello World!"));
}
}
});
return rootView;
}
Hope this helps.
UPDATE:
1 . Remove your FrameLayout inside fragment_main. Create a new layout named activity_main and add the FrameLayout into it (with an id) as:
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/container" />
2 . Set this layout in onCreate method into your Activity like:
// onCreate method Activity
setContentView(R.layout.activity_main);
3 . Then, remove static in your Fragment declaration, this should be:
public class PlaceholderFragment ... { }
4 . Finally, when you try to find ids elements inside onCreateView method, you ALWAYS MUST to use the inflated view as:
rootView.findViewById(R.id.some_id_example);
Voila! This should work now.

Eclipse 4 errors

These are the error messages I get:
Cannot cast from an int toEditText
EXTRA_MESSAGE cannot be resolved to variable
PlaceholderFragment cannot be resolved to type
The nested type DisplayMessageActivity cannot hide an enclosing type
This is my code
package com.example.thirdapp;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new
PlaceholderFragment()).commit();
}
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
/** Called when the user clicks the Send button */
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) (R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
}
}

You need to find the edit text view by id.
EditText editText = (EditText) view.findViewById(R.id.edit_message);

You need put the function "sendMessage" out of "PlaceholderFragment".
Here is mine:
public void sendMessage(View view) {
// Do something in response to button
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);
}

Develop Reference

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want to send text from one activity to another in android - android

In DisplayMessageActivity.java file comment out below code. There is no R.id.container in corresponding xml file. if (savedInstanceState == null) { getSupportFragmentManager().beginTransaction() .add(R.id.container, new PlaceholderFragment()).commit(); }

Have you added your DisplayMessageActivity in the AndroidManifest.xml in the application tag like: <activity android:label="#string/app_name" android:name=".DisplayMessageActivity"/>

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