CODEWITHSUNDEEP
javaandroidregextextviewhighlight
johnchen902
johnchen902

Reputation: 9599

Highlight text In TextView which might contains HTML tags

I want to make an application about regex. User input a regex and a test text, and I want to highlight everything in the test text that matches the regex. Now I've made something like this:

// txaTestText is an EditText
Editable testText = txaTestText.getText(); 

// pattern is a java.util.regex.Pattern input by user
Matcher matcher = pattern.matcher(testText);

// txaFindResult is a TextView
txaFindResult.setText(Html.fromHtml(matcher
        .replaceAll("<font color=\"red\">$0</font>")));

The issue is user may input some string including HTML tags as the test text. For example:

I tried to use Html.escapeHtml. However it is added in API level 16, while my minimum require is 8.

My question is how to solve the issue above?

Upvotes: 2

Views: 870

Answers (1)

Tobrun
Tobrun

Reputation: 18391

You should use Spans:

Spannables can be used to alternate parts of the TextView's text: e.g. color with ForeGroundColorSpan. It can even be used to introduce an image inline with the text (emoticons in a textmessage).

here is a hard coded example highlighting the <br> part. you should add the regex algorithme:

MainActivity.java

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView textView = (TextView)findViewById(R.id.helloworld);
        Spannable spannableString = new SpannableString(getString(R.string.hello_world));        
        spannableString.setSpan(new ForegroundColorSpan(Color.RED), 5, 10, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        textView.setText(spannableString);

    }

strings.xml

<string name="hello_world">
  <![CDATA[
    Hello <br> World 
  ]]>
</string>

main.xml

<TextView
    android:id="@+id/helloworld"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:text="@string/hello_world" />

Screenshot highlight <br> tag

Upvotes: 2

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