Android: how to make keyboard enter button say “Search” and handle its click?

In the layout set your input method options to search.

<EditText
    android:imeOptions="actionSearch" 
    android:inputType="text" />

In the java add the editor action listener.

editText.setOnEditorActionListener(new TextView.OnEditorActionListener() {
    @Override
    public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
        if (actionId == EditorInfo.IME_ACTION_SEARCH) {
            performSearch();
            return true;
        }
        return false;
    }
});