I am getting a null pointer exception at line 39 due to the text view being created in fragment.xml and its code being added in main activity class. What shall I do to the highlighted piece of code to make it work in the same way, but in the PlaceHolderFragment class?
package com.example.myfirstapp;
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.widget.DatePicker;
import android.widget.TextView;
import android.os.Build;
public class DisplayMessageActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/* setContentView(R.layout.activity_display_message);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
} */
getSupportActionBar().show();
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
***TextView textView = (TextView)findViewById(R.id.textView1);
textView.setTextSize(40);
textView.setText(message);***
// Set the text view as the activity layout
setContentView(R.layout.fragment_display_message);
}
#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;
}
}
}
The inflation of the textview should be inside the fragment class if it was added in the fragment layout(same as activity). So move the textview inside the onCreateView() method of the fragment. It should look something like this:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View view = inflater.inflate(R.layout.fragment_calendar, container,
false);
TextView textView = (TextView)view.findViewById(R.id.textView1);//make this a class variable
textView.setTextSize(40);//put this method in onStart()
textView.setText(message);//put this method in onStart()
return view;
}
hi i think you should write
// Create the text view
TextView textView = (TextView)findViewById(R.id.textView1);
textView.setTextSize(40);
textView.setText(message);
below
setContentView(R.layout.fragment_display_message);
Related
My intent is to get text from an EditText and view it in a Toast message. The code is this:
package com.example.primaapplicazione;
import android.app.Activity;
import android.app.ActionBar;
import android.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.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.os.Build;
public class MainActivity extends Activity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null)
{
getFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
public void fromEditToToast()
{
EditText e = (EditText)findViewById(R.id.editText1);
Button b = (Button)findViewById(R.id.button1);
b.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
}
});
}
#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;
}
}
}
If I call the method "fromEditToToast()" in onCreate() without the "setOnClickListener()", it compiles properly and the app opens. If I call the same method with that function on the emulator app doesn't open, showing this message "Unfortunately, PrimaApplicazione has stopped.
What should I have to do?
I have seen this is a very common error, The PlaceholderFragment uses the fragment_main.xml that must contain the elements editText1 and button1, probably you have that elements defined in your activity_main.xml
It may be that views are not being instantiated while the activity has started. Device works faster than emulator so it might work in a device while not in emulator.
Implement your onClickListener directly in fragment and show the toast from there, it will work (assuming EditText and Button lies in fragment).
Try following code in your fragment and call the following function in your fragment's onViewCreated function to set the button's listener : -
private void set buttonOnClickListener()
{
EditText e = (EditText)getView().findViewById(R.id.editText1);
Button b = (Button)getView().findViewById(R.id.button1);
b.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
//your code goes here;
}
});
}
I created a new Android project in Eclipse with one Blank Activity. In the fragment, I added a TextView called textHello. All I want to do for this test is to modify textHello's text value. But I'm my findViewById is giving me null.
Here is the fragment code:
<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.gcuitest.MainActivity$PlaceholderFragment" >
<TextView
android:id="#+id/textHello"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
</RelativeLayout>
Here is the MainActivity.java
package com.example.gcuitest;
import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
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.TextView;
import android.os.Build;
public class MainActivity extends Activity {
private TextView helloText;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
//getFragmentManager().beginTransaction()
// .add(R.id.container, new PlaceholderFragment()).commit();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.container, new PlaceholderFragment());
fragmentTransaction.commit();
}
helloText = (TextView) findViewById(R.id.textHello);
helloText.setText("Gerard");
}
#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;
}
}
}
Why is findViewById giving me null? Is it in the right place? I've looked at other code samples, and they place findViewById in onCreate, after setContentView, which is what this does. What did I miss? Thanks.
Why is findViewById giving me null?
Because textHello TextView is inside PlaceholderFragment layout instead of Activity which is activity_main.
if you want to access TextView from Fragment layout then use onCreateView as :
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_layout, container, false);
helloText = (TextView)view. findViewById(R.id.textHello);
helloText.setText("Gerard");
return view;
}
I dont know what happen with my sdk and eclipse. I install google services,it is install successfully but now i add activity to my old project but now .java file is extends FragementActivity. i dont know why this is happen. Please give reply please.
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;
public class WebViewActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.web_view);
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.web_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();
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;
}
}
}
I can't to get the button from fragment, what's wrong?
Recieve a uncaught exception - nullpointerexception;
Button can't be found.
Early all will be find, but after update android sdk, all is changed ((
package com.example.test;
import java.io.IOException;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity implements OnClickListener {
Button play, pause;
MediaPlayer mplayer;
RadioGroup rgroup;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.i("MyTAG", "1");
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
mplayer = new MediaPlayer();
rgroup = (RadioGroup) findViewById(R.id.radioGroup1);
play = (Button) findViewById(R.id.play);
pause = (Button) findViewById(R.id.pause);
play.setOnClickListener(this);
pause.setOnClickListener(this);
}
#Override
public void onClick(View v) {
}
#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;
}
}
}
p.s. sorry for my english
You are trying to search inside Activity's layout, and your widgets are inside a Fragment's layout.
Put your logic inside your PlaceHolderFragment class:
public static class PlaceholderFragment extends Fragment implements OnClickListener {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
mplayer = new MediaPlayer();
rgroup = (RadioGroup) rootView.findViewById(R.id.radioGroup1);
play = (Button) rootView.findViewById(R.id.play);
pause = (Button) rootView.findViewById(R.id.pause);
play.setOnClickListener(this);
pause.setOnClickListener(this);
return rootView;
}
#Override
public void onClick(View v) {
}
}
P.S. Салам алейкум =)
I am new to android development.I am trying to create an activity method on clicking a button.
Below is my MainActivity.java file code.
I am getting errors
1."cannot resolve method'setVisibility (int)'" and
2."cannot resolve symbol 'TextView'"
please guide.
MainActivity.java
package com.AndroidLove;
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;
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();
}
}
public void onLoveButtonClicked(View view) {
TextView textView =(TextView) findViewById(R.id.textView);
textView.setVisibility(View.VISIBLE);
}
#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.
switch (item.getItemId()) {
case 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;
}
}
}
Import this package as well
import android.widget.TextView;