How to make part of the text Bold in android at runtime?

Based on Imran Rana's answer, here is a generic, reusable method if you need to apply StyleSpans to several TextViews, with support for multiple languages (where indices are variable):

void setTextWithSpan(TextView textView, String text, String spanText, StyleSpan style) {
    SpannableStringBuilder sb = new SpannableStringBuilder(text);
    int start = text.indexOf(spanText);
    int end = start + spanText.length();
    sb.setSpan(style, start, end, Spannable.SPAN_INCLUSIVE_INCLUSIVE);
    textView.setText(sb);
}

Use it in an Activity like so:

@Override
protected void onCreate(Bundle savedInstanceState) {
    // ...

    StyleSpan boldStyle = new StyleSpan(Typeface.BOLD);
    setTextWithSpan((TextView) findViewById(R.id.welcome_text),
        getString(R.string.welcome_text),
        getString(R.string.welcome_text_bold),
        boldStyle);

    // ...
}

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strings.xml

<string name="welcome_text">Welcome to CompanyName</string>
<string name="welcome_text_bold">CompanyName</string>

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Result:

Welcome to CompanyName

Let's say you have a TextView called etx. You would then use the following code:

final SpannableStringBuilder sb = new SpannableStringBuilder("HELLOO");
      
final StyleSpan bss = new StyleSpan(android.graphics.Typeface.BOLD); // Span to make text bold
final StyleSpan iss = new StyleSpan(android.graphics.Typeface.ITALIC); //Span to make text italic
sb.setSpan(bss, 0, 4, Spannable.SPAN_INCLUSIVE_INCLUSIVE); // make first 4 characters Bold 
sb.setSpan(iss, 4, 6, Spannable.SPAN_INCLUSIVE_INCLUSIVE); // make last 2 characters Italic

etx.setText(sb);

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