Start an Activity from Item (ActionBar)? - java

I'm using ActionBarCompat to make an actionbar for devices under API 11.
It works great and was easy to setup, but I'm stuck.
I have some items on the Actionbar, and it looks great.
Some Items are behind the three dots (ifRoom) and some you always can see.
How do I make so when you click on one of these items so it starts an new Activity?
I tried with switch/case and other methods, but didnt work to send from one Activity to another through the Items. I know how to send from button, imagebutton to another Activity, but not from Items.
My main.xml looks like this:
<item
android:id="#+id/add"
android:title="Lägg till"
android:icon="#drawable/new"
android:orderInCategory="1"
budsnabben:showAsAction="always"/>
And the code in MainActivity looks like this:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.:
Intent intent = new Intent(this, MapActivity.class);
this.startActivity(intent);
break;
case R.id.menu_item2:
// another startActivity, this is for item with id "menu_item2"
break;
default:
return super.onOptionsItemSelected(item);
}
return true;
}
}
The problem is on case R.id.... After Id, I dont get my class map or main, its not there.
Thank you.
SOLUTION:
Just want to thank you Gerard.
I created new Strings in strings.xml.
After that, I did change the title in my main.xml to this:
android:title="#string/add"
I did hard-coded that line like before, therefore it didn't work I think:
android:title="#+id/add"
Thank you once more.

Use public boolean onOptionsItemSelected(MenuItem item) { ... } in your activity using the actionbar and create a switch-case matching item.getItemId() with the IDs from the menu layout. After that creating the appropriate intent like you would on a regular button.

Related

How to temporarily block the ability to click a menu item

I have a menu when I click on a specific element of which the activity opens, but the user can quickly click menu iten 2 times, which will lead to the opening of the activity 2 times. How can I block the ability to press a button after the first press?
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.create) {
// start activity
}
return super.onOptionsItemSelected(item);
}
I know about setEnabled, but when I return to enabled activity, it remains false, and it seems inconvenient to save MenuItem and return its state. Anyone have any ideas how to do this optimally?
I found the best solution to this problem. To do this, add the FLAG_ACTIVITY_CLEAR_TOP flag to the Intent. Thanks to this, it will be impossible to create 2 activities.
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

Prevent ActionBar back button to recreate the MainActivity

How can I prevent the ActionBar back button (we gonna say ABBB) of my SecondActivity to recreate the MainActivitywhen clicked ?
I have a ListView in the MainActivity and it can be edited using the SecondActivity. The problem is that when the user presses the ABBB, the ListView is reset to default...
However, when the user clicks my OK button or presses physical back button, there is not any problem because I'm using finish();
#Override
public void onBackPressed() {
finish();
}
If I use this code... :
switch (item.getItemId()) {
case (android.R.id.home):
finish();
}
...there is the same problem because, I guess, this method is called after "Android's code".
How can I totally override Android ABBB's clicked code to set it to just call finish(); ?
The ideal scenario is, when are you in the SecondActivity (I take it that, this means that you are in Edit mode), and you press the device back button or ABBB, you show a subtle alert to the user saying "do they really want to dismiss the editing", or go ahead and apply the edit done as in the Contacts application.
So that being said, if all you require is to finish() the activity on press of ABBB, the code that you shown above should work fine (though you need to put return true; after finish()). It works for me. Try the below one in your activity.
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
onBackPressed(); // or finish();
return true;
}
return super.onOptionsItemSelected(item);
}
I put onBackPressed(); because your ABBB with now imitate your device back button.
Or, you can set your parent activity's launch mode as -
android:launchMode="singleTop"
that will do all without changing anything.
Reference

Back button in header "refresh" the previus activity

I'm new to Android and I trying to do a simple app.
In the "home", I write my name and press the "send" button.
In the second page, the app show "Hello " + inserted name.
The problem is:
When I touch the back virtual button in nav bar, I come back to the home and in the input field there is always the name; but when I go back with the back button in header bar, the input field is empty.
I've tried with:
in onOptionsItemSelected:
switch (item.getItemId()){
case android.R.id.home:
Log.d("case","go back");
NavUtils.navigateUpFromSameTask(this); //or with finish();
return true;
}
it prints "case: go back" in console, but doesnt' work correcly.
My custom theme have as parent Theme.AppCompat.Light.DarkActionBar and if i put getSupportActionBar().setDisplayHomeAsUpEnabled(true); in onCreate, Android Studio tells me "Method invocation 'getSupportActionBar().setDisplayHomeAsUpEnabled(true)' may produce 'java.lang.NullPointerException'".
I solved adding this in the second Activity:
#Override
public Intent getSupportParentActivityIntent() {
return null;
}
and edit the switch/case function like this:
switch (item.getItemId()){
case android.R.id.home:
this.finish();
return false;
default:
return super.onOptionsItemSelected(item);
}

"Back" button on Action bar - Android . How to go "back"?

Action Bar
I'm talking about the (Number 1, in the pic), button with a little arrow and the app icon and the top left side of the screen. It is automatically defined when we select the "Black activity" template.
My app has a pretty huge hierarchy graph, got about 25 activities now.
I'm basically just showing a few tutorials and one can navigate to it according to the categories.
Now that "Back" (?) button thingy on action bar is on every screen I have, and I do want to keep it. The code shows no error, but when I actually press that button, the app stops working.
What I want, is to just replicate the actual back button function with that (Number 1) button, that I showed in the image.
When I press it, the top most screen should close, and the last one should open. Just close the screen.
What I tried :
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
this is the the function that inflates that buggy button along with the action bar. I tried to replace the entire code, and call "Finish" function, but that failed miserably.
I was unable to find a function specifically made for that top left most button...
I want the top most screen on the stack(the one in the foreground) to close, when this button is touched.
How to do this ?
I think the easiest way out is follows:
I am assuming that from activity A you are starting the activity B. Now from activity B you want to go back to activity A on pressing the top left back button on action bar. simply call this.finish() or ActivityName.this.finish() from there:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
this.finish();
return true;
}
return super.onOptionsItemSelected(item);
}
This should finish your current activity. However if you have lot of activities, then you might have to do this in all the activities. To save yourself from that effort, you can make a class lets call it AbstractActivity; that extends Activity. Then you can extend all your other activity classes to extend that class(AbstractActivity). Inside AbstractActivity you can put the above code. So now that piece of code would be valid for all your activities and that feature would be implemented for all of them. Basically this sort of thing (Inheritance)can be used any time, when there are some common features which would be applicable to your many classes.
If you are receiving any errors, please do post your LogCat if you require further help.
Hope this helps you.
just giving basic code given by #shobhit puri...
for invoking the action bar back button..add the following code in the onCreate() method along with the onOptionsItemSelected....
protected void onCreate(Bundle savedInstanceState)
{
ActionBar actionBar = getActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_information);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
this.finish();
return true;
}
return super.onOptionsItemSelected(item);
}

Android: Start a new activity from menu item

I'm Trying to open a second screen for my application. The user have to click on a menu item and then the screen must open. But what i try it always just ignores the rule after the case statement.
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.OpenScreen: startActivity(new Intent(this, SecondScreenActivity.class));;
break;
}
return true;
I've also added the activity to AndroidManifest.xml inside the tag.
Any help will be apreciated
Solution
I had the finish() in the constructor of the new class.
For me your java code is correct and work for me that way.
However when I learned Android, when I came at the point of starting a new activity I faced the same problem as you, nothing was happening, without any error, simply not working.
In my case I forgot to add the activity in the AndroidManifest.xml file. Perhaps it is the same for you.
Your AndroidManifest file should contain somewhere something like that
<activity
android:name=".SecondScreenActivity" >
</activity>
this tell the system that SecondScreenActivity exitst.
In
http://developer.android.com/guide/topics/manifest/activity-element.html they say :
All activities must be represented by elements in the manifest file. Any that are not declared there will not be seen by the system and will never be run.
Hope this helps
try like this
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.OpenScreen:
startActivity(new Intent(YourClass.this, SecondScreenActivity.class));
break;
}
return true;
Don't return true for onOptionsItemSelected.
call super method like this.
return super.onOptionsItemSelected(item);
instead of return true;

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