CODEWITHSUNDEEP
javaandroidcastingandroid-widget
gregghz
gregghz

Reputation: 3965

Force Close When Dynamically Creating Widget from XML in Android

I'm attempting to create a few radio buttons and add them a RadioGroup dynamically. When I use the LayoutInflater method of pulling in the xml and adding it to the current view, everything works fine. The correct radio buttons show up.

However when I try to cast the View that LayoutInflater.inflate returned to a RadioButton (so I can setText), I get a force close with a java.lang.ClassCastException.

for (int i = 0; i < options.length(); i++) {
  JSONObject option = options.getJSONObject(i);

  View option_view = vi.inflate(R.layout.poll_option, radio_group, true);
  option_view.setId(i);

  RadioButton rb = (RadioButton) option_view.findViewById(i);

  rb.setText(option.getString("response"));
}

poll_option.xml:

<RadioButton xmlns:android="http://schemas.android.com/apk/res/android"
             android:text="RadioButton" 
             android:layout_width="wrap_content" 
             android:layout_height="wrap_content" />

Upvotes: 1

Views: 465

Answers (3)

devunwired
devunwired

Reputation: 63293

The problem is you're not getting the views you think you're getting. LayoutInflater.inflate() called with a supplied root view means the view returned to you is THAT root view (not the inflated view). The method in which you are calling it inflates a new RadioButton and attaches it to the Group, but the return value (option_view) is the group itself, not the individual item. Since you need to play with the view before attaching it to the group, I'd recommend code like this (which works):

//I added these for posterity, I'm sure however you get these references is fine
LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
RadioGroup radio_group = new RadioGroup(this);
//Get the button, rename it, then add it to the group.
for(int i = 0; i < options.length(); i++) {
    JSONObject option = options.getJSONObject(i);

    RadioButton option_view = (RadioButton)vi.inflate(R.layout.poll_option, null);
    option_view.setText(option.getString("response"));

    radio_group.addView(button);
}

Editorial Note:

Just my $0.02, for such a simple layout, running this inflation process over and over in a loop may be a bit too much (inflation is expensive). You could easily create the same RadioButton in code, and add it with your LayoutParams, like:

LayoutParams params = new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
for (int i = 0; i < options.length(); i++) {
    RadioButton option_view = new RadioButton(this);
    option_view.setText(option.getString("response"));
    radio_group.addView(option_view, params);
}

This code I didn't test, but it should be pretty close :p

Hope that Helps!

Upvotes: 5

Dr.J
Dr.J

Reputation: 1218

you want to radiobutton.setId(INT) and then later get it by findViewById() to get the button.

The setID(Int) should be used when you dynamically create the button. You can now access it later with findViewById.

Upvotes: 0

psychotik
psychotik

Reputation: 39019

You probably want to use findViewById and locate the radio button in the inflated view. Something like:

RadioButton rb = (RadioButton)option_view.findViewById(R.id.yourButtonId);

See http://developer.android.com/reference/android/view/View.html#findViewById(int)

Upvotes: 1

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