Develop Reference

I need to enable or disable the POSITIVE button of an AlertDialog based on input fields and dismiss only on good validation

I would like to enable or disable the OK (POSITIVE) button of the AlertDialog with a custom layout such that I can:
Disable the OK button initially
Enable the OK button when all required fields have been entered
Disable the OK button again if a required field has been cleared
Perform validation after the OK button is selected and prevent dismissal upon validation errors
Assume the AlertDialog layout is as follows with one required field description and one optional field age:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<EditText
android:id="#+id/description"
android:hint="Field is required"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toTopOf="#id/age" />
<EditText
android:id="#+id/age"
android:hint="Optional"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="#id/description"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
Assume I have a button to kick off the dialog
Button b = findViewById(R.id.main_button);
b.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Log.e(TAG,"button");
View viewcustom = getLayoutInflater().inflate(R.layout.customdialog,null);
EditText edt1 = viewcustom.findViewById(R.id.description);
EditText edt2 = viewcustom.findViewById(R.id.age);
// render alertdialog
}
});

Here is the code. I created a custom layout with 2 EditText fields and require only 1 to be entered. The first is treated as just text that must be present and the second is treated as an optional Age. The final example shows how to add validation and to "not dismiss" after OK is pressed and validation fails.
The OK button is initially disabled and when data is entered in the first text field the OK button is enabled.
By controlling the enable/disable of the positive (OK) button it requires the user to the enter fields necessary (rather than giving them an error when omitted).
Note that when the user clears the same field the OK button is disabled.
You can also add a hint to the EditText field(s) to indicate required (shown in second example).
Note that this was used as reference for the EditText listening (as I linked to in comment).
Finally, the last demo shows if you really wanted to show an error on field validation after the OK button is enabled and pressed. (From here.)
This should be obvious how to expand it to all your EditText fields. And bear in mind you can an condition to enabling the OK button - here it is just at least one character.
Button b = findViewById(R.id.main_button);
b.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Log.e(TAG,"button");
View viewcustom = getLayoutInflater().inflate(R.layout.customdialog,null);
EditText edt1 = viewcustom.findViewById(R.id.description);
EditText edt2 = viewcustom.findViewById(R.id.age);
final AlertDialog.Builder alertDialog = new AlertDialog.Builder(MainActivity.this)
.setView(viewcustom)
.setPositiveButton("Ok", (dialogInterface, i) -> {
String d = edt1.getText().toString();
String a = edt2.getText().toString();
Toast.makeText(MainActivity.this,d, Toast.LENGTH_LONG).show();
});
alertDialog.setNegativeButton("Cancel", null);
AlertDialog ad = alertDialog.create();
edt1.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence sequence, int i, int i1, int i2) {}
#Override
public void onTextChanged(CharSequence sequence, int i, int i1, int i2) {}
#Override
public void afterTextChanged(Editable editable) {
if (edt1.getText().length() > 0) {
// if user enters anything then enable - modify criteria as desired
ad.getButton(DialogInterface.BUTTON_POSITIVE).setEnabled(true);
} else {
// if user deletes entry then back to disabled
ad.getButton(DialogInterface.BUTTON_POSITIVE).setEnabled(false);
}
}
});
// Initially OK button is disabled.
ad.show();
ad.getButton(DialogInterface.BUTTON_POSITIVE).setEnabled(false);
}
});
And demo:
You can also add a hint to each field to indicate it is required if nothing is entered as in :
<EditText
android:id="#+id/description"
android:hint="Field is required"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toTopOf="#id/age" />
Finally, if you really, really want to allow the OK but then do further validation to display errors then add the following. Note that the second field is treated as an Age field and the data entered must be an integer. A bit contrived but used to show an example.
// add this after the AlertDialog create()
ad.setOnShowListener(new DialogInterface.OnShowListener() {
#Override
public void onShow(DialogInterface anInterface) {
Button b = ad.getButton(DialogInterface.BUTTON_POSITIVE);
b.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// do some validation on edit text
String s = edt2.getText().toString();
try {
Integer age = Integer.valueOf(s);
Toast.makeText(MainActivity.this,d+":"+age, Toast.LENGTH_LONG).show();
ad.dismiss();
} catch (Exception e) {
// complain
Toast.makeText(MainActivity.this, "Age must be an integer", Toast.LENGTH_LONG).show();
}
}
});
}
});
And demo of requiring the optional Age to be an integer:

A variable holds an unexpected value

I'm building a module for checking an answer in my Android java app and it doesn't work. While debugging it shows that the variable holds a value that is completely unexpected for it to hold. Could please someone explain what the problem might be? Here is the module:
private void QuizOperations() {
Toast.makeText(QuizActivity.this,"quizOperation", Toast.LENGTH_SHORT).show();
answered = true; // when the question is already answered Set bool to true
RadioButton rbSelected = findViewById(rbGroup.getCheckedRadioButtonId());
int indexofchild =rbGroup.indexOfChild(rbSelected) +1;
int answerNr = indexofchild +1;
checkSolution(answerNr,rbSelected);// method checks if the answer that is selected by the user corresponds to the answer in the database
}
The intended way was rbselected getting the index of the RadioButton pressed by the user, and than answerNr gets the index of this button as int. Than it passes in to the checksolution() function which checks if the AnswerNr corresponds to the right answer in the database. However, while debugging answerNr holds the value of 5 whichever button I press.
Debug screenshot
Let me know if any additional code needed. Thanks a lot

Here is a very minimalistic example on how to detect the view is being pressed, set/get id from tag.
<?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:gravity="center"
android:orientation="vertical"
android:background="#333333">
<RadioButton
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:id="#+id/radioButton1"/>
<RadioButton
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:id="#+id/radioButton2"/>
<RadioButton
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:id="#+id/radioButton3"/>
</LinearLayout>
public class MainActivity extends AppCompatActivity implements View.OnClickListener
{
private String[] answers = {
"January",
"February",
"March",
};
private RadioButton rb1, rb2, rb3;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
rb1 = findViewById(R.id.radioButton1);
rb2 = findViewById(R.id.radioButton2);
rb3 = findViewById(R.id.radioButton3);
rb1.setTag("0");
rb2.setTag("1");
rb3.setTag("2");
rb1.setOnClickListener(this);
rb2.setOnClickListener(this);
rb3.setOnClickListener(this);
}
#Override
public void onClick(View view)
{
final int index = Integer.parseInt((String)view.getTag());
switch(view.getId()) {
case R.id.radioButton1:
rb2.setChecked(false);
rb3.setChecked(false);
Toast.makeText(MainActivity.this, answers[index], Toast.LENGTH_SHORT).show();
break;
case R.id.radioButton2:
rb1.setChecked(false);
rb3.setChecked(false);
Toast.makeText(MainActivity.this, answers[index], Toast.LENGTH_SHORT).show();
break;
case R.id.radioButton3:
rb1.setChecked(false);
rb2.setChecked(false);
Toast.makeText(MainActivity.this, answers[index], Toast.LENGTH_SHORT).show();
break;
}
}
}

How to create custom Android radio buttons?

I've got a couple radio button options in my android app, but I want them to look totally different. More something like below (quick mockup) in which you simply click the words you want and it makes them bold and underlined.
Does anybody know how I can achieve something like this? All tips are welcome!

Generally speaking, to override the look of default widgets, you'll need to create a drawable folder and put all of your xml definitions in that folder. Then reference that xml file within the RadioButton block of your layout.
Here's a good blog post on how to do all that:
http://blog.devminded.com/posts/custom-android-radiobutton

I know it might be late, but it is not a reason to keep the solution for myself.
1) You need to implement the .XML layout for the RadioGroup and it's RadioButtons. Set the RadioGroup children orientation with Horizontal value to display the button side by side. Setting the RadioButton button with #null value to hide the default selector
As following:
<RadioGroup
android:id="#+id/my_radiogroup"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<RadioButton
android:id="#+id/i_like_radiobutton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:button="#null"
android:padding="10dp"
android:text="I Like"
android:textColor="#android:color/holo_orange_light" />
<RadioButton
android:id="#+id/i_dont_like_radiobutton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:button="#null"
android:padding="10dp"
android:text="I Dont Like"
android:textColor="#android:color/holo_orange_light" />
</RadioGroup>
2) In your Activity class, initialize them and set their listener. The listener should keep track of the changes of the RadioButton changes and set the UI changes according to the state either select or unselect. As following:
RadioGroup myRadioGroup = (RadioGroup) findViewById(R.id.my_radiogroup);
RadioButton likeRadioButton = (RadioButton) findViewById(R.id.i_like_radiobutton);
RadioButton dontLikeRadioButton = (RadioButton) findViewById(R.id.i_dont_like_radiobutton);
//Like button listener
likeRadioButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (isChecked) {
//Make the text underlined
SpannableString content = new SpannableString(getString(R.string.like_text));
content.setSpan(new UnderlineSpan(), 0, content.length(), 0);
buttonView.setText(content);
//Make the text BOLD
buttonView.setTypeface(null, Typeface.BOLD);
} else {
//Change the color here and make the Text bold
SpannableString content = new SpannableString(getString(R.string.like_text));
content.setSpan(null, 0, content.length(), 0);
buttonView.setText(content);
buttonView.setTypeface(null, Typeface.NORMAL);
}
}
});
//Don't Like button listener
dontLikeRadioButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (isChecked) {
//Change the color here and make the Text bold
SpannableString content = new SpannableString(getString(R.string.like_text));
content.setSpan(new UnderlineSpan(), 0, content.length(), 0);
buttonView.setText(content);
buttonView.setTypeface(null, Typeface.BOLD);
} else {
//Change the color here and make the Text bold
SpannableString content = new SpannableString(getString(R.string.like_text));
content.setSpan(null, 0, content.length(), 0);
buttonView.setText(content);
buttonView.setTypeface(null, Typeface.NORMAL);
}
}
});
3) Now, the RadioButton will change it's color and it's TextStyle according to it's state automatically. You can add more customization if you want.
4) For performing the required action when the user select any of the Buttons, we need to override the setOnCheckedChangeListener method for the RadioGroup as following:
genderRadioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
if (checkedId == R.id.i_dont_like_radiobutton) {
//Do some actions
} else if (checkedId == R.id.i_like_radiobutton){
}
}
});
The final output will be very similar the the question image except the separator.
I hope it helps.

Get the index of a RadioGroup in Android

I have two RadioButton in a RadioGroup:
<RadioGroup
android:id="#+id/rgTripType"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="4" >
<RadioButton
android:id="#+id/rbOneWay"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:checked="true"
android:text="One Way" />
<RadioButton
android:id="#+id/rbRound"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Round" />
</RadioGroup>
I am calling the RadioGroup in my Java file as:
final RadioGroup rgTypeOfTrip = (RadioGroup) findViewById(R.id.rgTripType);
btnCalc.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Toast.makeText(MainActivity.this, CALL FUNCTION GETINDEX() to get value, Toast.LENGTH_SHORT).show();
});
rgTypeOfTrip.setOnCheckedChangeListener(new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
// TODO Auto-generated method stub
// Method 1
int pos=rgTypeOfTrip.indexOfChild(findViewById(checkedId));
getIndex(pos);
Toast.makeText(MainActivity.this, String.valueOf(pos), Toast.LENGTH_SHORT).show();
}
});
public int getIndex(int k) {
return k;
}
What it is supposed to do is display a Toast with the index of the radio button within the radio group. Instead, it causes my program to crash. Any idea how to resolve it?
UPDATE: The index issue is solved.
Issue: How can I use the index value (POS) in the btnClick function?

It crashes because pos is an integer change. If you pass an int value as second paramter you are asking android to look for a String with id the int you provide. If it does not exists the ResourcesNotFoundException will be thrown
Toast.makeText(MainActivity.this, pos, Toast.LENGTH_SHORT).show();
with
Toast.makeText(MainActivity.this, String.valueOf(pos), Toast.LENGTH_SHORT).show();

There are different way ..
I used this way
RadioGroup radiogroup = (RadioGroup) findViewById(R.id.groupid);
Button bt = (Button) findViewById(R.id.btnDisplay);
bt.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// get selected radio button from radioGroup
int selectedId = radiogroup.getCheckedRadioButtonId();
switch (selectedId) {
case R.id.radio_button1:
// do something..
break;
case R.id.radio_button2:
// do something..
break;
}
}
});

Android App Clicking Button Calls Incorrect OnClick Listener

I uploaded my app yesterday to Google Play and this morning I've wanted to make just a layout tweak as some of the text was overlapping buttons on smaller screens, basically I just want to move the buttons further down the screen. I thought this would be as easy as using eclipse's graphical editor... Nope.
I have no idea why but the small edit I've done to the position of the buttons on my "view_fact" layout has registered the buttons with the wrong OnClick listeners, there's only two buttons on the view and they're using eachothers event listeners and I have no idea why. I didn't touch the event listener code that was working perfectly on the old layout.
Here is my view_fact layout:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView
android:id="#+id/viewFactTitleText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="18dp"
android:text="#string/factTitleText"
android:textSize="22dp"
tools:context=".MainActivity" />
<ImageView
android:id="#+id/randomFactImage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/viewFactTitleText"
android:layout_centerHorizontal="true"
android:layout_marginTop="18dp"
android:contentDescription="Fact Image"
android:src="#drawable/canadaflag" />
<TextView
android:id="#+id/factData"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_below="#+id/randomFactImage"
android:layout_centerHorizontal="true"
android:layout_marginTop="14dp"
android:text="TextView" />
<Button
android:id="#+id/anotherFactButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/backToHomeButton"
android:layout_alignLeft="#+id/backToHomeButton"
android:layout_alignRight="#+id/backToHomeButton"
android:text="#string/anotherFactButtonText" />
<Button
android:id="#+id/backToHomeButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/factData"
android:layout_alignParentBottom="true"
android:layout_alignRight="#+id/factData"
android:text="#string/backToHomeButtonText" />
</RelativeLayout>
Listener and startup code:
public class MainActivity extends Activity {
/* Declaration of global variables */
private boolean debugMode = true; // Whether debugging is enabled or not
private static String logtag = "CanadianFacts"; // For use as the tag when logging
private TextView factData;
private int totalFacts = 72;
private String[][] facts = new String[totalFacts][5];
private int lastFact = 0;
/* Buttons */
/* Home page */
private Button randomFactButton;
/* View Fact page */
private Button anotherRandomFactButton;
private Button backToHomeButton;
/* About page */
private Button backToHomeFromAboutButton;
/* Image Views */
private ImageView randomFactImage;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/* Home Page Objects */
randomFactButton = (Button)findViewById(R.id.randomFactButton);
randomFactButton.setOnClickListener(randomFactListener); // Register the onClick listener with the implementation above
/* View Fact Page Objects */
/* Build Up Fact Array */
buildFactArray();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_about:
loadAboutPage(); // Call the loadAboutPage method
return true;
}
return false;
}
public void loadAboutPage() {
setContentView(R.layout.about);
/* Set up home page button listener */
backToHomeFromAboutButton = (Button)findViewById(R.id.backToHomeFromAboutButton);
backToHomeFromAboutButton.setOnClickListener(backToHomeListener); // We can reuse the backToHomeListener
}
/* Home Page Listeners */
//Create an anonymous implementation of OnClickListener, this needs to be done for each button, a new listener is created with an onClick method
private OnClickListener randomFactListener = new OnClickListener() {
public void onClick(View v) {
if (debugMode) {
Log.d(logtag,"onClick() called - randomFact button");
Toast.makeText(MainActivity.this, "The random fact button was clicked.", Toast.LENGTH_LONG).show();
}
setContentView(R.layout.view_fact); // Load the view fact page
/* We're now on the View Fact page, so elements on the page are now in our scope, instantiate them */
/* Another Random Fact Button */
anotherRandomFactButton = (Button)findViewById(R.id.anotherFactButton);
anotherRandomFactButton.setOnClickListener(anotherRandomFactListener); // Register the onClick listener with the implementation above
/* Back to Home Button */
backToHomeButton = (Button)findViewById(R.id.backToHomeButton);
backToHomeButton.setOnClickListener(backToHomeListener); // Register the onClick listener with the implementation above
// Get a random fact
String[] fact = getRandomFact();
if (fact[2] == null) { // If this fact doesn't have an image associated with it
fact[2] = getRandomImage();
}
int imageID = getDrawable(MainActivity.this, fact[2]);
/* See if this fact has an image available, if it doesn't select a random generic image */
randomFactImage = (ImageView) findViewById(R.id.randomFactImage);
randomFactImage.setImageResource(imageID);
factData = (TextView) findViewById(R.id.factData);
factData.setText(fact[1]);
if (debugMode) {
Log.d(logtag,"onClick() ended - randomFact button");
}
}
};
/* View Fact Page Listeners */
private OnClickListener anotherRandomFactListener = new OnClickListener() {
public void onClick(View v) {
if (debugMode) {
Log.d(logtag,"onClick() called - anotherRandomFact button");
Toast.makeText(MainActivity.this, "The another random fact button was clicked.", Toast.LENGTH_LONG).show();
}
// Get a random fact
String[] fact = getRandomFact();
if (fact[2] == null) { // If this fact doesn't have an image associated with it
fact[2] = getRandomImage();
}
int imageID = getDrawable(MainActivity.this, fact[2]); // Get the ID of the image
/* See if this fact has an image available, if it doesn't select a random generic image */
randomFactImage = (ImageView) findViewById(R.id.randomFactImage);
randomFactImage.setImageResource(imageID);
factData = (TextView) findViewById(R.id.factData);
factData.setText(fact[1]);
if (debugMode) {
Log.d(logtag,"onClick() ended - anotherRandomFact button");
}
}
};
private OnClickListener backToHomeListener = new OnClickListener() {
public void onClick(View v) {
if (debugMode) {
Log.d(logtag,"onClick() called - backToHome button");
Toast.makeText(MainActivity.this, "The back to home button was clicked.", Toast.LENGTH_LONG).show();
}
// Set content view back to the home page
setContentView(R.layout.main); // Load the home page
/* Reinstantiate home page buttons and listeners */
randomFactButton = (Button)findViewById(R.id.randomFactButton);
randomFactButton.setOnClickListener(randomFactListener); // Register the onClick listener with the implementation above
if (debugMode) {
Log.d(logtag,"onClick() ended - backToHome button");
}
}
};
Thank you.

I've managed to fix this, by moving the buttons around, changing the IDs a few times and then changing them back. And removing all of the align settings and resetting it's position.
A very strange problem, probably due to eclipse's graphical editor.