I'm building an Android application and I'm trying to build a user management system where users can login, logout, etc. I want to display a login menu item if the user is logged out and a logout button if the user is logged in. How can I do this dynamically?
This is the layout file right now:
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/add" android:title="Add" android:icon="@drawable/ic_menu_add"/>
<item android:id="@+id/list" android:title="List" android:icon="@drawable/ic_menu_list"/>
<item android:id="@+id/refresh" android:title="Refresh" android:icon="@drawable/ic_menu_refresh"/>
<item android:id="@+id/login" android:title="Login" android:icon="@drawable/ic_menu_login"/>
</menu>
This is my Java right now:
@Override
public boolean onCreateOptionsMenu(Menu menu) {
new MenuInflater(this).inflate(R.menu.activity_main, menu);
return(super.onCreateOptionsMenu(menu));
}
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
System.out.println(item.getItemId()==R.id.add);
if (item.getItemId()==R.id.add)
{
//Cannot add spot unless we have obtained the users current location.
if((currentLat != 0) && (currentLng != 0))
{
System.out.println("loggedin? : " + auth.isLoggedIn());
if(!auth.isLoggedIn())
{
Toast.makeText(MainActivity.this, "You must be logged in to add a new spot",
Toast.LENGTH_LONG).show();
}
else
{
Intent addIntent = new Intent(MainActivity.this, AddSpot.class);
Bundle b = new Bundle();
b.putDouble("currentLat", currentLat);
b.putDouble("currentLng", currentLng);
addIntent.putExtras(b);
startActivity(addIntent);
return(true);
}
}
}
else if(item.getItemId()==R.id.list)
{
//Pointless showing them a blank screen if nothing is retrieved from the server
if(list != null)
{
Intent listIntent = new Intent(MainActivity.this, ListLocations.class);
listIntent.putExtra("list", list);
startActivity(listIntent);
return(true);
}
}
if(item.getItemId()==R.id.refresh)
{
finish();
startActivity(getIntent());
return(true);
}
if(item.getItemId()==R.id.login)
{
Intent loginIntent = new Intent(MainActivity.this, LoginActivity.class);
startActivity(loginIntent);
return(true);
}
return(super.onOptionsItemSelected(item));
}
public class yourActivity extends Activity {
...
private static final int MENU_ADD = Menu.FIRST;
private static final int MENU_LIST = MENU.FIRST + 1;
private static final int MENU_REFRESH = MENU.FIRST + 2;
private static final int MENU_LOGIN = MENU.FIRST + 3;
/**
* Use if your menu is static (i.e. unchanging)
*/
/*
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
menu.add(0, MENU_ADD, Menu.NONE, R.string.your-add-text).setIcon(R.drawable.your-add-icon);
menu.add(0, MENU_LIST, Menu.NONE, R.string.your-list-text).setIcon(R.drawable.your-list-icon);
menu.add(0, MENU_REFRESH, Menu.NONE, R.string.your-refresh-text).setIcon(R.drawable.your-refresh-icon);
menu.add(0, MENU_LOGIN, Menu.NONE, R.string.your-login-text).setIcon(R.drawable.your-login-icon);
return true;
}
*/
/**
* Gets called every time the user presses the menu button.
* Use if your menu is dynamic.
*/
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
menu.clear();
if(enableAdd)
menu.add(0, MENU_ADD, Menu.NONE, R.string.your-add-text).setIcon(R.drawable.your-add-icon);
if(enableList)
menu.add(0, MENU_LIST, Menu.NONE, R.string.your-list-text).setIcon(R.drawable.your-list-icon);
if(enableRefresh)
menu.add(0, MENU_REFRESH, Menu.NONE, R.string.your-refresh-text).setIcon(R.drawable.your-refresh-icon);
if(enableLogin)
menu.add(0, MENU_LOGIN, Menu.NONE, R.string.your-login-text).setIcon(R.drawable.your-login-icon);
return super.onPrepareOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
super.onOptionsItemSelected(item);
switch (item.getItemId()) {
case MENU_ADD: doAddStuff(); break;
case MENU_LIST: doListStuff(); break;
case MENU_REFRESH: doRefreshStuff(); break;
case MENU_LOGIN: doLoginStuff(); break;
}
return false;
}
The following specific example adds a MENU_LOGOUT option if the user is logged in.
private static final int MENU_LOGOUT = MENU.FIRST + 4;
public boolean onPrepareOptionsMenu(Menu menu) {
...
if(auth.isLoggedIn()) {
menu.add(0, MENU_LOGOUT, Menu.NONE, R.string.your-logout-text).setIcon(R.drawable.your-logout-icon);
}
...
}
public boolean onOptionsItemSelected(MenuItem item) {
...
case MENU_LOGOUT:
if(auth.isLoggedIn()) {
doLogout();
} else {
Toast.makeText(this, "You must have somehow been logged out between the time the menu button was pressed and now.", Toast.DURATION_LONG).show();
}
break;
...
}
That's all there is to it.