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; klength; 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.