Develop Reference

mend.findItem explanation and confusion

I'm new to android development and kinda to Java as well.
I'm learning how to add buttons to actionbar - everything is working, but I don't understand few things.
//Showing small icons at actionbar
#Override
public boolean onCreateOptionsMenu(Menu menu){
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
menuItem = menu.findItem(R.id.recBin); // Finds the button in Actionbar and gets the ID
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.recBin: // Actions for delete button
dbHandler.remove(getID());
displayTaskList();
menuItem.setVisible(false); // Hide the button
break;
case R.id.editBtn: // Actions for editbutton
Toast.makeText(MainActivity.this,
"EDIT", Toast.LENGTH_LONG).show();
break;
case R.id.closeBtn:
Toast.makeText(MainActivity.this,
"CLOSE", Toast.LENGTH_LONG).show();
break;
default:
break;
}
return true;
}
This line: menuItem = menu.findItem(R.id.recBin); Is for what exactly? I took it off and my app crashed, so I understand that it's mandatory. What I don't understand is what icons ID should I put at bold space? It has to be from "menu" right, but does it matter which id I take? For instance, if I took R.id.closeBtn instead of recBin? As long as it's an id from menu, it works?
P.S. I hope this isn't a terrible question [probably is] and I'm sorry if so.
Solution:
Turns out you can simply get ID's. Stupid and simple.
private MenuItem item1, item2, item3;
//Showing small icons at actionbar
#Override
public boolean onCreateOptionsMenu(Menu menu){
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
item1 = menu.findItem(R.id.recBin); // Rec button
item2 = menu.findItem(R.id.editBtn); // Edit button
item3 = menu.findItem(R.id.closeBtn); // Close button
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.recBin: // Actions for delete button
dbHandler.remove(getID());
displayTaskList();
item1.setVisible(false); item2.setVisible(false); item3.setVisible(false); // Hiding all buttons
break;
case R.id.editBtn: // Actions for editbutton
item1.setVisible(false); item2.setVisible(false); item3.setVisible(false); // Hiding all buttons
break;
case R.id.closeBtn:
item1.setVisible(false); item2.setVisible(false); item3.setVisible(false); // Hiding all buttons
break;
default:
break;
}
return true;
}

It's a reference to MenuItem, but it would be easier if you do:
case R.id.recBin: // Actions for delete button
dbHandler.remove(getID());
displayTaskList();
item.setVisible(false); // Hide the button
break;
You can safely remove the reference afterwards

Menu shows when it shouldn't as I set it false

I've encountered another problem with my app. When the cat dies, I hit the "results screen" (it isn't a new activity but I hide all current elements and show a new text view indicating the death cause), and I want to hide the menu items, but for some reason it's not responding to isHeDead().
Basically the problem seems to be that it doesn't see "return false" inside onCreateOptionsMenu because for some reason isHeDead() isn't working there, even though the method works everywhere else.
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(fab_menu, menu);
while (!isHeDead()){
return true;
}
return false;
}
public Boolean isHeDead() {
TextView t = (TextView) findViewById(R.id.textDiedOf);
TextView textName = (TextView) findViewById(R.id.CatsTitleStats);
TextView textAge = (TextView) findViewById(R.id.CatsAgeStat);
TextView textStats1 = (TextView) findViewById(R.id.CatsStats);
TextView textStats2 = (TextView) findViewById(R.id.CatsStats2);
ImageView image = (ImageView) findViewById(R.id.imageViewCat);
if (cat.getAge() >= 20) {
textName.setVisibility(View.GONE);
textAge.setVisibility(View.GONE);
textStats1.setVisibility(View.GONE);
textStats2.setVisibility(View.GONE);
image.setVisibility(View.GONE);
t.setText("Sorry! " + getIntent().getStringExtra(KEY_NAME_EXTRA) + " died of old age.");
return true;
} else if (cat.getAnger() >= 10) {
textName.setVisibility(GONE);
textAge.setVisibility(View.GONE);
textStats1.setVisibility(View.GONE);
textStats2.setVisibility(View.GONE);
image.setVisibility(View.GONE);
t.setText("Sorry! " + getIntent().getStringExtra(KEY_NAME_EXTRA) + " died of madness.");
return true;
} ///etc...
}
User options (not sure if this has anything to do with the menu problem but still).
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
/// FEED ///
case R.id.action_feed:
int qualityRandom = (int) (Math.random() * 10);
if (qualityRandom == 5) {
cat.happy(-2);
cat.healthy(-30);
cat.angry(2);
cat.thirsty(2);
ageStat();
Stats1();
Stats2();
if (isHeDead()) {
break;
} else {
Toast.makeText(CatStatus.this, "Food was in a poor state...", Toast.LENGTH_SHORT).show();
break;
}
} else {
cat.happy(1);
cat.healthy(10);
cat.hungry(-3);
cat.angry(-1);
ageStat();
Stats1();
Stats2();
Toast.makeText(CatStatus.this, "Yummy!", Toast.LENGTH_SHORT).show();
break;
}
/// DRINK ///
case R.id.action_drink: ///etc...

When you hit results screen, if you are not going to a new activity, onCreateOptionsMenu is not being called!
You need to keep a reference to your menu:
private Menu myMenu;
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(fab_menu, menu);
this.myMenu = menu;
while (!isHeDead()){
return true;
}
return false;
}
And then, you can call inside your isHeDead() method like this:
menu.setGroupVisible(R.id.main_menu_group, false);
or:
menu.clear();
It depends on what you want.
Check this answer:
Hide/Show Action Bar Option Menu Item for different fragments

onCreateOptionsMenu is called only one time when the app launch activity

Android: Inflate menu (add items to action bar) only on click of a button

I am trying to inflate a menu only onclick of a button in android. How do i achieve it without creating it automatically by calling onCreateOptionsMenu.
I want the menu to appear only after button is click.

First add this icon in you action R.menu... file and set the visibility as false.
Have a boolean instance variable in our java file.
private boolean isTickVisible = false;
Then you need to override OnPrepareOptions menu like below and set the visibility of the tick menu.
#Override
public void onPrepareOptionsMenu(Menu menu) {
super.onPrepareOptionsMenu(menu);
MenuItem someMenuItem = menu.findItem(R.id.tick_menu_item);
someMenuItem.setVisible(isTickVisible);
}
Finally onClick event of your button do the following :
isTickVisible = true;
invalidateOptionsMenu(); //this will redraw your menu.

I fixed this issue by setting the visibility.Inflate the layout and make it visible only on clicking the button.Add a flag inside onClickListener
eg:Hide=true;
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_search, menu);
for (int i = 0; i < menu.size(); i++)
if(Hide){
menu.getItem(i).setVisible(true);
}
}

Android: show/hide menuitem based on number of items in the ListView

I have a ListView in my activity. I also have a menu and there is a menuitem for saving the list. I want to make it behave like the pseudocode below:
if (myList.size() > 0) {
menuitem.setVisible(true);
} else {
menuitem.setVisible(false);
}
I want the "save" menuitem to show only when there is at least one item in the listview. I have a custom ArrayAdapter implementation also, can this action be made from there? Or is there any kind of listener I could use?
Any help is appreciated!
EDIT:
JDev answer is the solution.
I changed only one thing: I moved the list size checking to notifyDataSetChanged() method inside my custom ArrayAdapter and now it works!
/**
* {#inheritDoc}
*/
#Override
public void notifyDataSetChanged() {
// Hide/show 'save' menuitem
if (mListItems.size() > 0) {
mListener.setMenuItemVisible(true);
} else {
mListener.setMenuItemVisible(false);
}
super.notifyDataSetChanged();
}

After getting the ListView length. Add invalidateOptionsMenu(); to call onCreateOptionsMenu().
Check if ListView is empty or not here,
#Override
public boolean onCreateOptionsMenu(Menu menu)
{
...
MenuItem menuitem = menu.findItem(R.id.addAction);
if (myList.size() > 0) {
menuitem.setVisible(true);
} else {
menuitem.setVisible(false);
}
}
Comment below if you have any query.

In your custom array adapter, you can do something like this:
CustomArrayAdapter.java
public interface MenuListener {
void setMenuItemVisible(boolean state);
}
private MenuListener mListener;
private Item[] mListItems; // The list of items that your adapter handles
public void setMenuListener(MenuListener listener) {
mListener = listener;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ListView listview = convertView.findViewById(R.id.yourListViewId);
if (mListItems.size() > 0) {
mListener.setMenuItemVisible(true);
} else {
mListener.setMenuItemVisible(false);
}
}
Activity.java:
public class Activity implements CustomArrayAdapter.MenuListener {
private MenuItem menuItem; // The menu item that you wanna show/hide
....
#Override
public void onCreate(Bundle savedInstanceState) {
CustomArrayAdapter adapter = new CustomArrayAdapter(params...);
adapter.setMenuListener(this);
// Set listView adapter
}
#Override
public boolean onCreateOptionsMenu(Menu menu)
{
menuItem = menu.findItem(R.id.menuItemId); // Save the menu item that you want to show/hide later
...
}
#Override
public void setMenuItemVisible(boolean state) {
menuItem.setVisible(state);
}
}

You shouldn't have to implement listeners or other convoluted methods for something as simple as this. In your Activity, simply add one line (after you've fetched your array to be passed on to your adapter):
menuitem.setVisible(array!= null && array.length() > 0 ? true: false);
// array.length() / array.length / array.size() -- whichever is suitable
EDIT: if you're allowing users to add/remove from the list, then disregard the one-liner above. You could simply include your Activity as a parameter to your adapter's constructor. In your activity, add a public method such as:
public void showHideMenuItem(int size) {
menuitem.setVisible(size > 0 ? true: false);
}
In your adapter, call the above method from wherever you're allowing adding/removing of items:
activity.showHideMenuItem(items.getCount());
To set the menuitem's visibility initially, call:
showHideMenuItem(0); // from your Activity's onCreate(), or
activity.showHideMenuItem(0); // from your adapter's constructor
If you've solved this via listener etc and you're happy with it, that's ok, I just personally wouldn't complicate stuff if it isn't necessary. I'd also prefer to determine the menuitem's visibility via the size of the array held by the adapter vs. the number of items in the listview.

Changing a Menu Item Icon during run time

How can I change an Menu Item icon during run time according to an If statement ? This is the code that I have and it results in a crash.
public boolean onPrepareOptionsMenu(Menu Item) {
if (favorite == true){
itema = (MenuItem) findViewById(R.id.action_search);
itema.setIcon(R.drawable.ic_action_importants);
}
return true;
}

You are calling the Activity's findViewById, you should have more luck by calling Menu findItem.
public boolean onPrepareOptionsMenu(Menu menu)
{
MenuItem myMenuItem = menu.findItem(R.id.myMenuItemId);
myMenuItem.setIcon(R.drawable.ic_myAction);
return true;
}