Normy posted:

Is anyone else doing that Coursera Android development course that was posted by someone awhile ago? I find it a little hard to follow. Like the lectures don't really explain what the assignments are asking you to do. This one here: https://class.coursera.org/android-001

Glimm posted:

I'm not sure the Gradle build system functions with Eclipse at the moment. Maybe try Android Studio?

fritz posted:

but I'm getting a java.lang.NoSuchMethodException from eclipse:

code:

com.example.drawer.MainActivity.TheView failed to instantiate.

It builds and does something anyway tho, but the TheView is taking up the whole display.

NoDamage posted:

So onRetainNonConfigurationInstance() is deprecated, which I was using to store my AsyncTasks when my Activities are re-created during rotation. The suggested solution is to store it in Fragment with setRetainInstance(true), which seems a bit bizarre to me. Is this really the recommended method for saving AsyncTasks between configuration changes? Shove it in an interface-less Fragment?

Karthe posted:

What are my options if I want to implement a two-column ListView? A single-column ListView will waste too much space on larger devices like a Nexus 7, so I'd like to switch to a two-column mode on them. Something like this:

Phones

code:

[     List	]
|	A	|
|	B	|
|	C	|
|	D	|
[_______E_______]

Tablets

code:

[	       List		]
|	  A	||	  B	|
|	  C	||	  D	|
|	  E	|		|
[_______________________________]

Would it be as simple as loading a tablet layout that has a GridView instead of a ListView?

Glimm posted:

Yeah using the GridView in the tablet layout is the way to go, you should even be able to reuse your adapter!

Karthe posted:

My god, that was easier than I could have imagined. After making the new layout the only thing I had to change in my code was to switch references of ListView to AbsListView instead. Thanks!

Tunga posted:

Looks like Color.toString() doesn't have defined behaviour so probably avoid just putting the object in the log output.

Other than that, you didn't really describe what problem you are actually having. What behaviour are you seeing?

Doctor w-rw-rw- posted:

What are you smoking? There's no object being printed here. The problem is clear - the color isn't being set.

Doctor w-rw-rw- posted:

-2^24 is 0xFF000000. In ARGB this means a totally opaque black. This means that red, green, and blue are consistently zero. Take a look at your constructor and you'll see you never actually set the instance variables.

I assume you're new to programming, if not in general, then at least to Java. You would do well (generally) to recognize certain powers of two, and (specifically) learn how to use Java's debugger. Those will go a long way in helping you solve your problems in the future. Luckily, Java is one of the easiest languages to use a debugger with IMO, its other shortcomings aside.

Literally Elvis posted:

I am new-ish to programming, and you were totally right. By using Java's debugger, do you mean jdb or things like breakpoints in Android Studio?

I'm unsure if my use of Log.d() is appropriate or not. I've been using it the way I've used it above because it's helpful to see the filtered output in logcat for diagnosing various problems (though this didn't help, and presumably breakpoints would have). Should I be using them more frequently/sparingly?

Uncomfortable Gaze posted:

You can use a RelativeLayout to have views overlap each other. Make sure to place the buttons below the custom view in the XML file, they will draw over anything above them. RelativeLayout offers the "android:layout_alignParentBottom" and related arguments to help you position everything the way you want.

fritz posted:

That's what I thought I was doing, but no luck:

Uncomfortable Gaze posted:

You are on the right track, but the major problem is here:

code:

		TV = new TrailView(this);
		setContentView(TV);

You should be calling setContentView(R.layout.whatever_activity_layout) and that should be happening in onCreate(). The contents of that XML file are only used when you specify that layout in the setContentView call.

e: Also, anything configuring views (like setting the button onClickListener) should happen shortly after the setContentView call in onCreate, not in onResume. Anything in onResume will happen every time the screen turns off, the user hits the home button and returns, or you launch another activity and return.

The activity lifecycle is really critical, make sure you read through this page: http://developer.android.com/reference/android/app/Activity.html

To clarify, you will need something like this in onCreate:

code:

setContentView(R.layout.activity_main);
TV = (TrailView) findViewById(R.id.trailview);  //set android:id="@+id/trailview" for the TrailView in your XML
myButtonOne = (Button) findViewById(R.id.button1);
myButtonOne.setOnClickListener(ect ect)

Uncomfortable Gaze posted:

Oh, right, having the TrailView inside the activity class complicates things. It's usually better to split them into separate classes.

To reference it like you have now you'll need to use the generic view item in the layout xml:

code:

<view class="com.example.drawer.MainActivity$TrailView"
	android:layout_width="match_parent"
	ect ect />

e: The dollar sign indicates that the class is an inner class.

fritz posted:

Oh, cool, that worked (plus I had to change the constructor in the View to take an AttributeSet and make some fields static).

Thanks!



ETA: also the reason I nested the classes is because I wanted the inner class to see state belonging to the parent class, I suppose I should have implemented getter/setter methods in TrailView instead and call those?

Uncomfortable Gaze posted:

Yea, the normal way to handle this is to split the view class into a separate file and interface with it like any other class. Once you get the hang of it you'll figure out the proper separation of concerns and an easy way to communicate between view and activity. It's probably little daunting to jump straight into a custom view as part of your first app.

fritz posted:

Let me go try pulling out the view class and I'll be back with questions.

fritz posted:

OK, so I made a TrailView.java and put all the TrailView code in there, then updated activity_main.xml:

<view class="com.example.drawer.TrailView"
android:id="@+id/trailview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@+id/button1"
android:layout_alignParentRight="true" />
and it works.

But (and this was happening before) in onCreate I do:

code:

TV = (TrailView)findViewById(R.id.trailview);

and TV is null.

Uncomfortable Gaze posted:

With the class separated you can use the normal class syntax:

code:

<com.example.drawer.TrailView
    android:id="@+id/trailview" 
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    .../>

The findViewById call must happen after setContentView, the views are not created until the setContentView call.
The TrailView class is extending View, right?

fritz posted:

Uncomfortable Gaze posted:

Odd, you should be working at this point, especially if you can get buttons that exist on the same layout. Only thing slightly unusual is that you don't need class="com.example.drawer.TrailView" anymore, that's handled by the tag itself. If you can't get it to work can you post a gist with the current activity code in full?

Jo posted:

Some beginner conceptual questions here. I'm not grokking the logical flow of the average Android app. I can use Buttons in Views to signal Intents which trigger changes to new Activities which have different Views, yes? Or have I completely lost it? Fragments, then, are when you have n ways of looking at the same data and don't want to pass it between activities?

Jo posted:

Some beginner conceptual questions here. I'm not grokking the logical flow of the average Android app. I can use Buttons in Views to signal Intents which trigger changes to new Activities which have different Views, yes? Or have I completely lost it? Fragments, then, are when you have n ways of looking at the same data and don't want to pass it between activities?