What is "context menu" & method registerForContextMenu()

Question

In Activity class, there is method called registerForContextMenu(View view).

The android document explains that this method is used to registers a context menu to be shown for the given view (multiple views can show the context menu).

• What does "context menu" mean? Does it mean the physical menu button or what?
• I also need some explanation about the method registerForContextMenu(View view), it is not clear to me to just read the document online.

Answer 1

It's basically a pop-up menu that is displayed when you long-click certain UI elements (usually an item in a ListView).

You should take a look at the Menus section of the Developer Guide.

Answer 2

This is from Android Developers: Menu -Android Developers

A context menu is a floating menu that appears when the user performs a long-click on an element. It provides actions that affect the selected content or context frame.

Imagine that you want a conext menu in a listview

//Constants for context menu options
public static final int MENU_MARK = 1;
public static final int MENU_REMOVE = 2;

public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    ...
    ...
    // Specify that your listview has a context menu attached
    registerForContextMenu(getListView());
}

// here you create the context menu
@Override
public void onCreateContextMenu(ContextMenu menu, View v, 
   ContextMenuInfo menuInfo) {
  menu.add(Menu.NONE, MENU_MARK, Menu.NONE, "MARK");
  menu.add(Menu.NONE, MENU_REMOVE, Menu.NONE, "Remove");
}

// This is executed when the user selects an option
@Override
public boolean onContextItemSelected(MenuItem item) {
AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
switch (item.getItemId()) {
    case MENU_MARK:
        mark_item(info.id);
        return true;
    case MENU_REMOVE:
        delete_item(info.id);
        return true;
    default:
        return super.onContextItemSelected(item);
   }
}