I'm attempting to change a TextView between two activities. The problem is, when I change the text in the other activity from main activity, it works fine, the screen goes to the other activity and the text has been changed. However I have another button which takes me to the other activity from Main, but the newly updated text has disappeared when I press it. Any help?
MyActivity.java
public class MyActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
final EditText et = (EditText) findViewById(R.id.editText1);
Button b = (Button) findViewById(R.id.button1);
b.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(MyActivity.this, Second.class);
intent.putExtra("thetext", et.getText().toString());
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.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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void onClickGoToActivity(View view) {
setContentView(R.layout.second);
}
}
Second.java
public class Second extends Activity{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second);
TextView tv = (TextView) findViewById(R.id.textView1);
tv.setText(getIntent().getExtras().getString("thetext"));
}
}
activity_my.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:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin"
tools:context=".MyActivity">
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/editText1"
android:layout_centerHorizontal="true"
android:hint="Change me"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/button1"
android:layout_centerHorizontal="true"
android:layout_marginTop="50dp"
android:text="Add text in other activity"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/go_to_activity_button"
android:text="Go to activity"
android:layout_centerHorizontal="true"
android:layout_marginTop="200dp"
android:onClick="onClickGoToActivity"/>
</RelativeLayout>
second.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">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/textView1"
android:textSize="30sp"/>
</LinearLayout>
AndroidManifest.xml
Second class activity:
I presume the problem lies here:
public void onClickGoToActivity(View view) {
setContentView(R.layout.second);
}
where the newly changed TextView is being reset back to the original layout (where the TextView is empty with no text). I'm not sure how to fix this as I'm new to Android.
Thank you.
changing content view of activity is a bad idea to start another activity. Simply you just do the same thing which is
public void onClickGoToActivity(View view) {
Intent intent = new Intent(MyActivity.this, Second.class);
intent.putExtra("thetext", et.getText().toString());
startActivity(intent);
}
Related
I have MainActivity which has got a button that opens Activity 2. Everything from Activity 2 should be calculated and be run but the user should rest at MainActivity? How do I do this?
I found a solution where I dont run the "setContentView()" but then my app crashes.
You want to change the view of application but does not want the user to change activity.
Use two different layout in xml file with id :
<?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">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:id="#+id/first_view">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button1"
android:id="#+id/button"
android:background="#358a32" />
</LinearLayout>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:id="#+id/second_view"
android:visibility="gone">
</LinearLayout>
<LinearLayout>
Then onclick of button :
public class MainActivity extends Activity {
boolean firstViewOff = false;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button button = (Button) findViewById(R.id.button1);
LinearLayout first_view = (LinearLayout) findViewById(R.id.first_view);
LinearLayout second_view = (LinearLayout) findViewById(R.id.second_view);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
firstViewOff = true;
first_view.setVisibility(View.GONE);
second_view.setVisibility(View.VISIBLE);
}
});
}
#override
public void onBackPressed(){
super.onBackPressed();
if(firstViewOff){
second_view.setVisibility(View.GONE);
first_view.setVisibility(View.VISIBLE);
firstViewOff = false;
}
}
}
Why i attached backpressed :
Because when user backpress then it will just directly show firstview without closing,
I am trying to make an android code that provide a different work for each button.
so when the user press on Button1 a Textview field provides " you pressed on Button1"
my question is about the correct place that I can instantiate the Textview ONLY ONCE as the only working place is inside the Button1 Function.
Java Code for a single button:
public void Button1(View view) {
final TextView textView=(TextView)findViewById(R.id.textView2);
textView.setText("You clicked the button 1");
}
total java code
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
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);
}
public void Button1(View view) {
final TextView textView=(TextView)findViewById(R.id.textView2);
textView.setText("You clicked the button 1");
}
public void Button2(View view) {
final TextView textView=(TextView)findViewById(R.id.textView2);
textView.setText("You clicked the button 2");
}
public void Button3(View view) {
final TextView textView=(TextView)findViewById(R.id.textView2);
textView.setText("You clicked the button 3");
}
public void Button4(View view) {
final TextView textView=(TextView)findViewById(R.id.textView2);
textView.setText("You clicked the button 4");
}
public void Button5(View view) {
final TextView textView=(TextView)findViewById(R.id.textView2);
textView.setText("You clicked the button 5");
}
public void Button6(View view) {
final TextView textView=(TextView)findViewById(R.id.textView2);
textView.setText("You clicked the button 6");
}
}
Total XML Code
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/RelativeLayoutID"
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"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context="com.example.sherifsaleh.xmllayout.MainActivity"
tools:showIn="#layout/activity_main"
>
<Button
android:id="#+id/button3"
android:onClick="Button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="3"
android:layout_above="#+id/button6"
android:layout_alignLeft="#+id/button6"
android:layout_alignStart="#+id/button6" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="Button6"
android:text="6"
android:id="#+id/button6"
android:layout_below="#+id/button2"
android:layout_alignLeft="#+id/button9"
android:layout_alignStart="#+id/button9" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="9"
android:id="#+id/button9"
android:onClick="Button9"
android:layout_alignTop="#+id/button8"
android:layout_toRightOf="#+id/button8"
android:layout_toEndOf="#+id/button8" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="8"
android:id="#+id/button8"
android:layout_below="#+id/button5"
android:layout_toRightOf="#+id/button4"
android:layout_toEndOf="#+id/button4"
android:onClick="Button8"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="2"
android:onClick="Button2"
android:id="#+id/button2"
android:layout_above="#+id/button5"
android:layout_toRightOf="#+id/button1"
android:layout_toEndOf="#+id/button1" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="Button5"
android:text="5"
android:id="#+id/button5"
android:layout_below="#+id/button1"
android:layout_toRightOf="#+id/button1"
android:layout_toEndOf="#+id/button1" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="1"
android:onClick="Button1"
android:layout_above="#+id/button4"
android:layout_alignLeft="#+id/button4"
android:layout_alignStart="#+id/button4" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="4"
android:id="#+id/button4"
android:layout_above="#+id/button7"
android:layout_alignLeft="#+id/button7"
android:layout_alignStart="#+id/button7" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="7"
android:id="#+id/button7"
android:layout_alignParentBottom="true"
android:layout_alignLeft="#+id/textView2"
android:layout_alignStart="#+id/textView2"
android:layout_marginBottom="90dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textIsSelectable="true"
android:text="New Text"
android:id="#+id/textView2"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="80dp"
android:textSize="50dp"/>
</RelativeLayout>
Try like this.
public class MainActivity extends AppCompatActivity {
private TextView textView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView)findViewById(R.id.textView2);
....
}
And your Button click method as
public void Button1(View view) {
textView.setText("You clicked the button 1");
}
1)First try to initialize your references in onCreate which loads once.So references to your views will initialize only once
eg-
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnOne = (Button) findViewById(R.id.btnOne);
btnTwo = (Button) findViewById(R.id.btnTwo);
textView = (TextView) findViewById(R.id.textView);
btnOne.setOnClickListener(this);
btnTwo.setOnClickListener(this);
}
2)Instead of calling seperate methods for each button apply click listeners on buttons as above mentioned
and implement View.OnClickListener and then
3)Override method
#Override
public void onClick(View v) {
Button b = (Button)v;
String buttonText = b.getText().toString();
textView.setText("You clicked on " + buttonText);
}
So the code in onClick is repeating in your case instead of writing each time seperately write it once and get text or you can set Tag of button and get it(in case when you want to set another value to textview instead of button text) and set to textview as i did in onClick.
It will reduce your efforts and increase your code reusability and redability too..!!!!!
Not super sure what your question is. If your asking if it's acceptable to do your findViewById in the button listener, it's acceptable but not optional. Every time you press the button the code runs. It's better to do it once in onCreate
Simply declare it at the start of your Activity
public class MainActivity extends AppCompatActivity {
private TextView textView2;
.....
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_layout);
textView2 = (TextView) findViewById(R.id.textView2);}
.....
public void Button6(View view) {
textView2.setText("bla");
}
Is that what you asked for ?
i have some problems with my layout, this is the capture of my layout inflater
the layout is to big and the button are in wrong place, i don't use a title but there is a black title background in there
i just want to make it smaller like piano tiles layout
can anyone help me to fix this?
this is my layout.xml data that will show inflater layout in menu.java
<?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:layout_gravity="center"
android:background="#drawable/backgroundblankwhite"
android:gravity="center|center_horizontal|center_vertical"
android:orientation="vertical"
android:padding="10sp" >
<TextView
android:id="#+id/exitimage"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#drawable/textinflateexit"
android:singleLine="true" >
<requestFocus />
</TextView>
<LinearLayout
android:id="#+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center" >
<Button
android:id="#+id/buttonexityes"
android:layout_width="120dp"
android:layout_height="wrap_content"
android:background="#drawable/buttonquityes" />
<Button
android:id="#+id/buttonexitno"
android:layout_width="120dp"
android:layout_height="wrap_content"
android:background="#drawable/buttonquitno" />
</LinearLayout>
</LinearLayout>
and this is my menu.java that have a button to display my inflate layout
public class menu extends Activity {
private Context context = this;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.menu);
Button exit = (Button) findViewById(R.id.exit);
exit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
final Dialog openDialog = new Dialog(context);
openDialog.setContentView(R.layout.inflatequitapp);
TextView dialogTextContent = (TextView)openDialog.findViewById(R.id.exitimage);
Button dialogExitButton = (Button)openDialog.findViewById(R.id.buttonexityes);
dialogExitButton.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
// if this button is clicked, close
// current activity
menu.this.finish();
}
});
Button dialogCloseButton = (Button)openDialog.findViewById(R.id.buttonexitno);
dialogCloseButton.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
openDialog.dismiss();
}
});
openDialog.show();
}
});
}
#Override
public void onBackPressed() {
// do nothing.
}
#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);
}
}
}
I have change a bit variable to check at my end..please do change variables,class to match at your end...
MainActivity.java
///---////
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
Button exit = (Button) findViewById(R.id.but);
exit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
final Dialog openDialog = new Dialog(MainActivity.this);
openDialog.setContentView(R.layout.main);
openDialog.setTitle("Confirm Exit");
TextView dialogTextContent = (TextView)openDialog.findViewById(R.id.exitimage);
Button dialogExitButton = (Button)openDialog.findViewById(R.id.buttonexityes);
dialogExitButton.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v) {
finish();
}
});
Button dialogCloseButton = (Button)openDialog.findViewById(R.id.buttonexitno);
dialogCloseButton.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v) {
openDialog.dismiss();
}
});
openDialog.show();
}
});
}
Dialog xml file..
<?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:layout_gravity="center"
android:background="#ffffff"
android:gravity="center|center_horizontal|center_vertical"
android:orientation="vertical"
android:padding="10sp" >
<TextView
android:id="#+id/exitimage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#ffffff"
android:singleLine="true"
android:text="Are You Sure!!" >
<requestFocus />
</TextView>
<LinearLayout
android:id="#+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center" >
<Button
android:id="#+id/buttonexityes"
android:layout_width="120dp"
android:layout_height="wrap_content"
android:background="#ffffff"
android:text="Yes" />
<Button
android:id="#+id/buttonexitno"
android:layout_width="120dp"
android:layout_height="wrap_content"
android:background="#ffffff"
android:text="No" />
</LinearLayout>
</LinearLayout>
output:
you have to used below code for dialog
private void forgotPasswordDialog() {
LayoutInflater layoutInflater = LayoutInflater.from(this);
final View dialogView = layoutInflater.inflate(R.layout.dialog_forgot_password, null);
AlertDialog.Builder builder = new AlertDialog.Builder(this, R.style.PauseDialog);
final AlertDialog dialog = builder.create();
dialog.setView(dialogView);
dialog.show();
final EditText edtUserNameDialog = (EditText) dialogView.findViewById(R.id.edtUserNameDialog);
edtUserNameDialog.setText(edtUserName.getText());
final Button btnSubmit = (Button) dialogView.findViewById(R.id.btnSubmit);
btnSubmit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (!FieldsValidator.validateUsername(edtUserNameDialog)) {
//forgotPasswordDialog();
} else if (!checkDMSID()) {
KeyboardUtils.hideKeyboard(edtUserNameDialog);
dialog.dismiss();
} else {
KeyboardUtils.hideKeyboard(edtUserNameDialog);
forgotPassword(edtUserNameDialog.getText().toString());
dialog.dismiss();
}
}
});
final Button btnCancel = (Button) dialogView.findViewById(R.id.btnCancel);
btnCancel.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
KeyboardUtils.hideKeyboard(edtUserNameDialog);
dialog.dismiss();
}
});
}
I am trying to create an application using Android Studio. I used the default login activity template and then created a new separate sign-up activity. It is crashing with a NullPointerException. I tried to link the two activities together like this:
LoginActivity.java:
public class LoginActivity extends Activity implements LoaderCallbacks<Cursor> {
/**
* A dummy authentication store containing known user names and passwords.
* TODO: remove after connecting to a real authentication system.
*/
private static final String[] DUMMY_CREDENTIALS = new String[]{
"foo#example.com:hello", "bar#example.com:world"
};
/**
* Keep track of the login task to ensure we can cancel it if requested.
*/
private UserLoginTask mAuthTask = null;
// UI references.
private AutoCompleteTextView mEmailView;
private EditText mPasswordView;
private View mProgressView;
private View mLoginFormView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login2);
Button mSignUpTextView;
mSignUpTextView = (Button)findViewById(R.id.SignUpButton);
mSignUpTextView.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v) {
Intent intent = new Intent(LoginActivity.this, SignUpActivity.class);
startActivity(intent);
}
});
// Set up the login form.
mEmailView = (AutoCompleteTextView) findViewById(R.id.email);
populateAutoComplete();
mPasswordView = (EditText) findViewById(R.id.password);
mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
#Override
public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) {
if (id == R.id.login || id == EditorInfo.IME_NULL) {
attemptLogin();
return true;
}
return false;
}
});
Button mEmailSignInButton = (Button) findViewById(R.id.email_sign_in_button);
mEmailSignInButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
attemptLogin();
}
});
mLoginFormView = findViewById(R.id.login_form);
mProgressView = findViewById(R.id.login_progress);
}
And SignUpActivity.java:
public class SignUpActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sign_up);
}
#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_sign_up, 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);
}
}
And the activity_login2.xml file is:
<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: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.redux.kumardivyarajat.attendance.LoginActivity"
android:weightSum="1"
android:id="#+id/activity_login2">
<!-- Login progress -->
<ProgressBar android:id="#+id/login_progress"
style="?android:attr/progressBarStyleLarge"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:visibility="gone" />
<ScrollView android:id="#+id/login_form"
android:layout_width="match_parent"
android:layout_height="174dp">
<LinearLayout android:id="#+id/email_login_form"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:weightSum="1"
android:touchscreenBlocksFocus="false">
<AutoCompleteTextView
android:id="#+id/email"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/prompt_email"
android:inputType="textEmailAddress"
android:maxLines="1"
android:singleLine="true"
android:layout_weight="10.63">
<requestFocus/>
</AutoCompleteTextView>
<EditText android:id="#+id/password"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/prompt_password"
android:imeActionId="#+id/login"
android:imeActionLabel="#string/action_sign_in_short"
android:imeOptions="actionUnspecified"
android:inputType="textPassword"
android:maxLines="1"
android:singleLine="true" />
<Button android:id="#+id/email_sign_in_button"
style="?android:textAppearanceSmall"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="#string/action_sign_in_short"
android:textStyle="bold" />
</LinearLayout>
</ScrollView>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/SignupText"
android:text="#string/sign_up_from_login"
android:textColor="#ffff0500" />
<Button
style="?android:textAppearanceSmall"
android:id="#+id/SignUpButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Sign Up"
android:textStyle="bold"
android:layout_gravity="center_horizontal" />
</LinearLayout>
Before adding the new signup button on the login activity, the app was working fine, but now it crashes immediately.
The logcat shows a NullPointerException:
04-03 19:29:44.486 4648-4648/com.redux.kumardivyarajat.attendance E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.redux.kumardivyarajat.attendance, PID: 4648
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.redux.kumardivyarajat.attendance/com.redux.kumardivyarajat.attendance.LoginActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2190)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2239)
at android.app.ActivityThread.access$800(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1202)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5047)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:806)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.redux.kumardivyarajat.attendance.LoginActivity.onCreate(LoginActivity.java:69)
at android.app.Activity.performCreate(Activity.java:5249)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2154)
I understand the usual causes of a NullPointerException but I am having trouble identifying how it is possible in my code. How can I solve this?
Turns out that because some elements of my app weren't available for API level 14 and below, separate activity_login2.xml and activity_login2.xml(v14) files had been auto generated.
The NullPointerException was because of the fact that the new sign-up button wasn't defined in the second activity_login2.xml(v14) file. I've updated that file and now the app is working fine.
Can you please check last 2 elements - Edittext
android:id="#+id/SignupText"
and Button
android:id="#+id/SignUpButton"
are having valid parent layout or not?
I can see no parent layout defined for these UI elements.
I want to add a button to clear the numbers on textfield by tapping on the button.
(Reset my EditText back to an empty "space" after a button has pressed that would have completed an activity with input from the EditText field.)
Cheers! Thanks!
ActivityMain XML file!
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/back"
android:orientation="vertical"
tools:context="com.miuapps.unitconverter.Centimetres_Metres" >
<TextView
android:id="#+id/textView1" //first textview
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Enter a Value(cm) :"
android:layout_gravity="center"
android:gravity="center"
android:textSize="30dp"/>
<EditText
android:id="#+id/editText1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:inputType="number" />
<Button
android:id="#+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Convert" />
<TextView
android:id="#+id/tvDisplay1" //output textview
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="In Metres: 0"
android:textSize="30dp" />
</LinearLayout>
double counter, counter2 = 100;
double x;
Button conv;
TextView dis1, dis2;
EditText ent1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
counter = 0;
conv = (Button)findViewById(R.id.button1);
dis1 = (TextView)findViewById(R.id.tvDisplay1);
//dis2 = (TextView)findViewById(R.id.tvDisplay2);
ent1 = (EditText)findViewById(R.id.editText1);
conv.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
x = new Integer(ent1.getText().toString());
counter = x/100;
//counter2++;
dis1.setText("In Metres: " +counter);
//dis2.setText("In Centimetres: " +counter2);
}
});
}
#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);
}
}
How about this:
ent1.setText("");
just put it at the end of your onClick Method
Edit:
conv.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// here you get the text from your editText
x = new Integer(ent1.getText().toString());
// do something with the text
counter = x/100;
// set result in another TextView
dis1.setText("In Metres: " +counter);
// work is done, so the editText can be cleared
ent1.setText("");
}
});
Edit 2 (reset button):
resetButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// reset only by another button
ent1.setText("");
}
});
Simply add a button in your layout.
<Button
android:id="#+id/buttonReset"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Reset" />
Find that button in your activity:
Button mButtonReset = (Button) findViewById(R.id.buttonReset);
mButtonReset.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View view){
ent1.setText("");
}
});
First Create Design,
Activity_main.xml like below,
<EditText
android:id="#+id/txt_1"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_marginTop="50dp"
android:ems="10"
android:hint="Enter Name"
android:inputType="textPersonName"
android:minHeight="48dp" />
<Button
android:id="#+id/btn_ok"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="50dp"
android:text="Button" />
<Button
android:id="#+id/btn_cln"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:text="Clear" />
**Then go to MainActivity.java edit code like below, **
**
public class MainActivity extends AppCompatActivity {
Button button,button2;
EditText editText;
String name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = findViewById(R.id.btn_ok);
editText = findViewById(R.id.txt_1);
button2 = findViewById(R.id.btn_cln);
//create text add button
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
name = editText.getText().toString();
}
});
//clean,reset text button
button2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
editText.setText("");
}
});
}
}
**