如何为Android ListView实现过滤器

Question

I have array of model object data, and i am displaying the text and image in listview from the model object array in my custom ArrayAdapter.

Its like android contact view, i want to implement the search functionality.

Can any one please advice me, how to implement filter for custom adapter which shows data from model object.

Sample example link or snippet of code is also fine.

Answer 1

You just have to filter underlying collection ( like this: What is the best way to filter a Java Collection? )

When filter condition changes, you just signal that dataset is changed and use filtered list instance to provide amount of entries and individual views

Answer 2

I actually don't like the approach where you duplicate your original list. It is both time consuming and memory consuming. I took the approach of just making the wanted items VISIBLE and the unwanted items GONE. My example is for a TableLayout where I filter the TableRows, each has a TextView.

public void filter(TableLayout tl, String regex) {
    TableRow tr;
    TextView tv;
    Pattern p;
    Matcher m;

    p = Pattern.compile(regex);
    int n = tl.getChildCount();
    for(int i = 0; i < n; i++) {
        tr = (TableRow) tl.getChildAt(i);
        tv = (TextView) tr.getChildAt(0);
        m = p.matcher(tv.getText());
        if(m.find()) {
            tr.setVisibility(View.VISIBLE);
        } else {
            tr.setVisibility(View.GONE);
    }
}

I did not profile it, but I am quite sure it is faster than copying all elements of a list and then filtering and then displaying the new list.

The advantage should be more noticeable as your list grows larger.

But, a caveat, I have to confess that although it works very well filtering a few hundreds of rows, I am concerned what happens when the number of rows is so big that it takes more than 5 sec to do the filtering. It should then trigger the App not responding dialog.
I tried to make it a thread, but because I directly deal with the views visibility I get an error message that only the original thread can touch the views. I am working on it and I am sure I will find a solution.