When the user marks some text (inside of an EditText, WebView...) a floating text selection popup appears, where apps can add custom items. Can som
This blog tutorial will show you how: https://medium.com/google-developers/custom-text-selection-actions-with-action-process-text-191f792d2999
Basically, in your Manifest file, add PROCESS_TEXT intent filter to the activity that will handle the text shared from popup menu.
Then, you would process that text in your Activity like this
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.process_text_main);
CharSequence text = getIntent()
.getCharSequenceExtra(Intent.EXTRA_PROCESS_TEXT);
// process the text
}