Checkbox Text List :: Extension of Iconified Text tutorial

 Checkbox Text List :: Extension of Iconified Text tutorial


What you will learn: How to create a list of items with Checkboxes 

Difficulty: 2.0 / 5 


What it will look like: 

Description: 
This tutorial grew from another tutorial here which dealt with making lists with icons attached to each list item. (IconifiedTextView tutorial). 

1. In order to make a List which includes checkboxes, we need to modify a few things. In CheckBoxifiedText.java, we made a String to hold the text of our list item. We also need a boolean value to keep track of the status of the checkbox (checked = true, unchecked = false). The constructor will initialize the checkbox to be checked or unchecked.

Java:

public  class CheckBoxifiedText  implements Comparable {  private  String mText =  "";  private  boolean mChecked;  public CheckBoxifiedText ( String text,  boolean checked )  {  /* constructor */  mText = text;  mChecked = checked;  }

2. Second, we need to look at CheckboxifiedTextViewAdapter.java. We need to add code to support our checkbox. (src.getChecked()will tell us whether our box is checked or not. 

Java:

public  View getView ( int position,  View convertView, ViewGroup parent ) {  CheckBoxifiedTextView btv;  if  (convertView ==  null )  {  btv =  new CheckBoxifiedTextView (mContext, mItems. get (position ) );  }  else  {  // Reuse/Overwrite the View passed  // We are assuming(!) that it is castable!  CheckBoxifiedText src = mItems. get (position );  btv =  (CheckBoxifiedTextView ) convertView;  btv. setCheckBoxState (src. getChecked ( ) );  btv =  (CheckBoxifiedTextView ) convertView;  btv. setText (mItems. get (position ). getText ( ) );  }  return btv;  }

We also want to add some methods for doing things like getting the state of the checkbox, or selecting all the items. 

Java:

public  void selectAll ( ) {  for (CheckBoxifiedText cboxtxt: mItems )  cboxtxt. setChecked ( true );  /* Things have changed, do a redraw. */  this. notifyDataSetInvalidated ( );  }

3. Open up CheckBoxifiedTextView.java. We need to set up where we want the checkbox to be located, the text location, and whether the box is checked or not. 

Java:

public CheckBoxifiedTextView ( Context context, CheckBoxifiedText aCheckBoxifiedText )  {  super (context );  /* First CheckBox and the Text to the right (horizontal),  * not above and below (vertical) */  this. setOrientation (HORIZONTAL );  mCheckBoxText = aCheckBoxifiedText;  mCheckBox =  new CheckBox (context );  mCheckBox. setPadding ( 0,  0,  20,  0 );  // 5px to the right  /* Set the initial state of the checkbox. */  mCheckBox. setChecked (aCheckBoxifiedText. getChecked ( ) );  /* At first, add the CheckBox to ourself  * (! we are extending LinearLayout) */  addView (mCheckBox,  new LinearLayout. LayoutParams (  LayoutParams. WRAP_CONTENT, LayoutParams. WRAP_CONTENT ) );  mText =  new TextView (context );  mText. setText (aCheckBoxifiedText. getText ( ) );  //mText.setPadding(0, 0, 15, 0);  addView (mText,  new LinearLayout. LayoutParams (  LayoutParams. WRAP_CONTENT, LayoutParams. WRAP_CONTENT ) );  }

4. Finally, we can look at our ListActivity code which will be using the classes we just made. In the attached source code, this is theCheckbox.java file. For this example, i am using an array of strings which contain the text we want in each list item. We create a checkboxlist adapter, cbla, first. 

Then, we loop through each item in the array and add it to the list adapter (using cbla.addItem()). I am setting all the checkboxes to initially be unchecked by passing the value of FALSE. 

Java:

public  class  Checkbox  extends ListActivity  {  /** Called when the activity is first created. */  private CheckBoxifiedTextListAdapter cbla;  // Create CheckBox List Adapter, cbla  private  String [ ] items =  { "Box 1",  "Box 2",  "Box 3",  "Box 4" };  // Array of string we want to display in our list  @Override  public  void onCreate (Bundle icicle )  {  super. onCreate (icicle );  setContentView (R. layout. main );  cbla =  new CheckBoxifiedTextListAdapter ( this );  for ( int k= 0; k length; k++ )  {  cbla. addItem ( new CheckBoxifiedText (items [k ],  false ) );  }  // Display it  setListAdapter (cbla );  }  }

Thats pretty much it. Not much work! Attached are all the source files you will need for this tutorial. I have also added functions such as select all, and deselect all which will come in handy.