Android Text Search
The Android guide for Search Overview is oriented towards searching external content rather than text. There is a mention of Using the Search Dialog. However all the bits you need are there. To get a search dialog in the toolbar that pops up when needed, you need a seach item in the menu. It should be the first item, unless there is a good reason otherwise.
<?xml version="1.0" encoding="utf-8"?>
<menu
xmlns:android="http://schemas.android.com/apk/res/android"
<item
android:id="@+id/search"
android:showAsAction="ifRoom|collapseActionView"
android:title="@string/search"
android:actionViewClass="android.widget.SearchView"
android:icon="@drawable/ic_action_search" />
The search dialog will still pop up if the search item is in the menu rather than the toolbar. The dialog pops up and collapses all by itself in response to user interaction without any developer code. To implement the search, you need an OnQueryTextListener, which is called by the SearchView.
// onCreateOptionsMenu
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
searchItem = menu.findItem(R.id.search);
searchView = (SearchView) searchItem.getActionView();
if (searchView != null)
{
searchView.setSubmitButtonEnabled(true);
searchView.setImeOptions(EditorInfo.IME_ACTION_GO);
searchView.setOnQueryTextListener(new QueryTextListener());
}
return true;
}
Get an extra submit button in the toolbar, change the keyboard button to a right arrow, and set the listener
Interactive Case Insensitive Search
// QueryTextListener
private class QueryTextListener
implements SearchView.OnQueryTextListener
{
private BackgroundColorSpan span = new
BackgroundColorSpan(Color.YELLOW);
private Editable editable;
private Pattern pattern;
private Matcher matcher;
private String text;
private int index;
private int height;
// onQueryTextChange
@Override
@SuppressWarnings("deprecation")
public boolean onQueryTextChange (String newText)
{
// Use web view functionality
if (shown)
markdownView.findAll(newText);
// Use regex search and spannable for highlighting
else
{
height = scrollView.getHeight();
editable = textView.getEditableText();
text = textView.getText().toString();
// Reset the index and clear highlighting
if (newText.length() == 0)
{
index = 0;
editable.removeSpan(span);
}
// Get pattern
pattern = Pattern.compile(newText,
Pattern.CASE_INSENSITIVE |
Pattern.LITERAL |
Pattern.UNICODE_CASE);
// Find text
matcher = pattern.matcher(text);
if (matcher.find(index))
{
// Get index
index = matcher.start();
// Get text position
int line = textView.getLayout()
.getLineForOffset(index);
int pos = textView.getLayout()
.getLineBaseline(line);
// Scroll to it
scrollView.scrollTo(0, pos - height / 2);
// Highlight it
editable
.setSpan(span, index, index +
newText.length(),
Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
return true;
}
// onQueryTextSubmit
@Override
public boolean onQueryTextSubmit (String query)
{
// Use web view functionality
if (shown)
markdownView.findNext(true);
// Use regex search and spannable for highlighting
else
{
// Find next text
if (matcher.find())
{
// Get index
index = matcher.start();
// Get text position
int line = textView.getLayout()
.getLineForOffset(index);
int pos = textView.getLayout()
.getLineBaseline(line);
// Scroll to it
scrollView.scrollTo(0, pos - height / 2);
// Highlight it
editable
.setSpan(span, index, index +
query.length(),
Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
}
// Reset matcher
if (matcher.hitEnd())
matcher.reset();
}
return true;
}
}
This implementation searches both a WebView, and a
TextView. The search is interactive, the highlighting and scroll
position moves as the user types. The search button on the keyboard
provides the ‘find next’ function. The web view search functionality
is built in, all the developer has to do is call the relevant methods,
findAll() and findNext(). The method findAll() is
deprecated as of android 16, but this code is supporting android 14,
which is the reason for the @SuppressWarnings("deprecation").
To provide nearly identical functionality in a text view requires the
use of regular expression search, and highlighting using a spannable
char sequence. The pattern uses the CASE_INSENSITIVE, LITERAL and
UNICODE_CASE flags so the search is case insensitive. The current
search index is provided to the matcher find() method so the search
stays in position if the user deletes search text, duplicating web
view functionality.
Interactive Regular Expression Search
// QueryTextListener
private class QueryTextListener
implements SearchView.OnQueryTextListener
{
private BackgroundColorSpan span = new
BackgroundColorSpan(Color.YELLOW);
private Editable editable;
private Matcher matcher;
private Pattern pattern;
private String text;
private int index;
private int height;
// onQueryTextChange
@Override
@SuppressWarnings("deprecation")
public boolean onQueryTextChange (String newText)
{
// Use regex search and spannable for highlighting
height = scrollView.getHeight();
editable = textView.getEditableText();
text = textView.getText().toString();
// Check text
if (text.length() == 0)
return false;
// Reset the index and clear highlighting
if (newText.length() == 0)
{
index = 0;
editable.removeSpan(span);
return false;
}
// Check pattern
try
{
pattern = Pattern.compile(newText, Pattern.MULTILINE);
matcher = pattern.matcher(text);
}
catch (Exception e)
{
return false;
}
// Find text
if (matcher.find(index))
{
// Get index
index = matcher.start();
// Check layout
if (textView.getLayout() == null)
return false;
// Get text position
int line = textView.getLayout()
.getLineForOffset(index);
int pos = textView.getLayout()
.getLineBaseline(line);
// Scroll to it
scrollView.scrollTo(0, pos - height / 2);
// Highlight it
editable
.setSpan(span, matcher.start(), matcher.end(),
Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
}
else
index = 0;
return true;
}
// onQueryTextSubmit
@Override
public boolean onQueryTextSubmit (String query)
{
// Find next text
if (matcher.find())
{
// Get index
index = matcher.start();
// Get text position
int line = textView.getLayout()
.getLineForOffset(index);
int pos = textView.getLayout()
.getLineBaseline(line);
// Scroll to it
scrollView.scrollTo(0, pos - height / 2);
// Highlight it
editable
.setSpan(span, matcher.start(), matcher.end(),
Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
}
else
{
matcher.reset();
index = 0;
}
return true;
}
}
The regular expression may become invalid as the user types, so the
Pattern.compile() statement is wrapped with a try statement to
trap any exceptions. The matcher.find(index) statement with an index
always searches from the index, the matcher.find() statement without
the index does ‘find next’. The check of the text view layout is to
deal with a null pointer exception when the user loads a file. The
matcher.reset() statement makes the search begin again from the
start.
// onOptionsItemSelected
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
// ...
default:
return super.onOptionsItemSelected(item);
}
// Close text search
if (searchItem.isActionViewExpanded())
searchItem.collapseActionView();
return true;
}
If the highlight isn’t removed when the user does something via the menu, like loading another file, it won’t go away, so it is removed before that happens. Collapsing the search view clears the search text, so the callback removes the highlight.
Find text in files
// findAll
public void findAll()
{
// Get search string
final String search = searchView.getQuery().toString();
Pattern pattern = Pattern.compile(search,
Pattern.CASE_INSENSITIVE |
Pattern.LITERAL |
Pattern.UNICODE_CASE);
// Get entry list
List<Calendar> entries = getEntries();
// Create a list of matches
List<String> matches = new ArrayList<String>();
// Check the entries
for (Calendar entry: entries)
{
File file = getDay(entry.get(Calendar.YEAR),
entry.get(Calendar.MONTH),
entry.get(Calendar.DATE));
Matcher matcher = pattern.matcher(read(file));
if (matcher.find())
matches.add(DateFormat.getDateInstance(DateFormat.MEDIUM)
.format(entry.getTime()));
}
// If found pop up a dialog
if (!matches.isEmpty())
{
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle(R.string.findAll);
final String[] choices = matches.toArray(new String[0]);
builder.setItems(choices, new DialogInterface.OnClickListener()
{
public void onClick (DialogInterface dialog,
int which)
{
String choice = choices[which];
DateFormat format =
DateFormat.getDateInstance(DateFormat.MEDIUM);
// Get the entry chosen
try
{
Date date = format.parse(choice);
Calendar entry = Calendar.getInstance();
entry.setTime(date);
changeDate(entry);
// Put the search text back - why it
// disappears I have no idea or why I have
// to do it after a delay
searchView.postDelayed(new Runnable()
{
// run
@Override
public void run()
{
searchView.setQuery(search, false);
}
}, FIND_DELAY);
}
catch (Exception e) {}
}
});
builder.setNegativeButton(android.R.string.cancel, null);
builder.show();
}
}
In this application the method getEntries() returns a list of
Calendar objects corresponding to stored files. The method
getDay() returns a File object for the file corresponding to that
date and the method read() returns the text in the file. The code
builds a list of strings corresponding the the matching files to
present to the user.
If the list isn’t empty an AlertDialog is built to display the
list. The OnClickListener parses the date and changes the app date
to the selected entry. For reasons best known to whoever wrote the
android SearchView code, the search text disappears while all this
is going on, so it is put back after a delay, otherwise it doesn’t
work.
See Also
- Flutter app bar search widget
- Android Navigation Menu
- Update App Widget
- Create a Word Grid
- Android Flutter