Implementing "Drilldown" navigation in Android App UI - android

I am trying to learn how to do stuff in Android, and I'm not sure of the best way to build the interface.
I've been working on porting an iPhone app, which uses navigation controllers and table views for looking at the different sections: basically, someone touches a cell in the table, which drills down to another table. when they touch a cell on that table it drills down to a webview that displays the information.
I want to do something similar for the android app, but I don't know how, or if there is a better way native to Android. I've figured out how to use the webview to my purposes, but moving forward and backward in the table tree is unclear.

So on an iphone when you say drill down I guess you mean when a user touches-up on a list row and it slides a new view on from the right, most of the time it has a nav bar at the top to give the user the option to go back?
The way android handles this is simply by starting a new activity. So you would have your 'Books' ListActivity when a listItem is clicked you would define a new intent that starts your 'Chapters' ListActivity and so on. The nav bar at the top of an iphone is not standard UI in android as most people see the dedicated 'back' key as a way of getting back to the previews screen.
This is how you start an intent in case you haven't seen it before:
Intent chaptersIntent = new Intent(this, Chapters.class);
this.startActivity(chaptersIntent);
This article is worth a quick read through as it explains Activities perfectly
http://d.android.com/guide/topics/fundamentals.html
Also have a look at the android version of TableView - ListView:
http://d.android.com/reference/android/widget/ListView.html
and ListActivity:
http://d.android.com/reference/android/app/ListActivity.html
EDIT:: Sample Code
I would do it something like this
public class Books extends ListActivity {
private String[] mBooks = new String[]{ "Book1", "Book2", "Book3", "Book4" };
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ArrayAdapter<String> booksAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,
android.R.id.text1,
mBooks);
this.setListAdapter(booksAdapter);
}
#Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
Intent mViewChaptersIntent = new Intent(this, Chapters.class);
mViewChaptersIntent.putExtra("BookName", mBooks[position]);
startActivity(mViewChaptersIntent);
}
}
So you pass through the id of the book as an extra to the Intent then in your Chapters Activity you get that extra in the onCreate method:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Bundle extras = getIntent().getExtras();
if(extras != null) {
String bookId = extras.getString("BookName");
}
}
Finally make sure all new activities are added to your AndroidManifest.xml file:
<activity android:name=".YourClassName"
android:label="#string/activity_name"
>
</activity>
Hope that helps

The primary way that the Android ui is created is using xml. I'm not exactly sure what you mean when you say drill down but if you want it to change views its as simple as making one set of xml elements visible and another set not. Check out the developer pages for more help.
http://developer.android.com/guide/topics/ui/index.html
Forgot to mention this is also a very good beginner resource.
http://mobiforge.com/designing/story/understanding-user-interface-android-part-1-layouts

As already pointed out XML way of doing layouts is most preferred.
basically, someone touches a cell in
the table, which drills down to
another table. when they touch a cell
on that table it drills down to a
webview that displays the information.
From what I understood from the term drills down, this may be wat you need
http://developer.android.com/guide/topics/ui/ui-events.html
From official docs
An event listener is an interface in
the View class that contains a single
callback method. These methods will be
called by the Android framework when
the View to which the listener has
been registered is triggered by user
interaction with the item in the UI.

Related

Programmatically show Layout to preface an activity

What I want to do:
I want to have multiple activities each prefaced with a page explaining to the user what the activity is about.
What I'm currently doing:
So my main class BaseModuleActivity extends Activity and I am trying to write a function called showTutorial() which will explain the next steps to the users.
Here is my attempt in doing so:
public void showTutorial(String title, String explanation){
setContentView(R.layout.tutorial_screen);
TextView tv1 = (TextView)findViewById(R.id.tutoTextTitle);
tv1.setText(title);
TextView tv2 = (TextView)findViewById(R.id.tutoTextExplanation);
tv2.setText(explanation);
findViewById(R.id.tutoButton).setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
//remove the tutorial's view
findViewById(R.id.tutoLayout).setVisibility(View.GONE);
}
});
}
And this method is called in the following:
public class myFirstActivity extends BaseModuleActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
//First show tuto
super.showTutorial(getString(R.string.upTitle),getString(R.string.upExplanation));
//TODO then actually do the activity stuff
/*
(findViewById(R.id.next_button)).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
finish();
}
});
*/
}
}
Problem:
I think the problem is mainly conceptual. I don't know the best approach to do this and the approach I'm taking is not working.
What I'm doing is not working because the view just become empty. I thought setting the visibility of the linearLayout to gone would make it disappear and the actual activity will able to take place.
What I need:
I need to understand if I can do what I want with my approach or not? Or what approach should I take.
I found some similar questions. However, the answer to these questions didn't seem to fit my problem.
I also looked into layout inflater and fragment, but layout inflater seem to be more for listView and fragment uses layout inflater.
Well, there are some approaches to show a guide for your activity (or application).
First one, and probably the easiest, is to show a dialog/TextView when user enters an activity and explain the activity guide in that dialog/TextView using plain text. From your explanation, I think this one is what your are trying to do.
Second one is to use something like slides with pictures to explain about your activity (like Google Sheets application).
Third one is to explain each control in your activity separatly by highlighting them (similar to how Go Launcher explains its feature on first launch)
You can find more info in below links:
How to implement first launch tutorial like Android Lollipop apps: Like Sheets, Slides app?
Android - first launch interactive tutorial
Seems that what you want is actually an introduction. Take a look at this project:
https://github.com/rubengees/introduction
From each introduction page you can launch the correspondent activity.

What's the correct way of displaying ViewPager after associated ListView's item click?

I'm a beginner in Android, so I apologize for the mistakes and I'd appreciate any constructive criticism.
I'm writing a basic application with a ListView of images, and when the user clicks on an item in the list, I want to display that image in a ViewPager, where the user can swipe back and forth to browse the whole list of images. Afterwards when the user presses the back button, I want to switch back to the ListView.
I manage the business logic in the MainActivity, which uses MainActivityFragment for the ListView and ImageHolderFragment for ViewPager.
The simplified code so far is as follows:
#Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mListItems = new ArrayList<>();
mListItemAdapter = new ListItemAdapter(this, R.layout.list_item, R.id.list_item_name, mListItems);
mListView = (ListView) findViewById(R.id.list_view_content);
mListView.setAdapter(mListItemAdapter);
mDeletedListItems = new ArrayList<>();
mViewPager = (ViewPager) getLayoutInflater().inflate(R.layout.image_display, null, true);
mImageAdapter = new ImageAdapter(getSupportFragmentManager(), mListItems);
mViewPager.setAdapter(mImageAdapter);
mViewPager.setOffscreenPageLimit(3);
mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
mViewPager.setCurrentItem(position);
setContentView(mViewPager); // TODO: this is very wrong!
}
});
loadImages();
noContentText = (TextView) findViewById(R.id.no_content_text);
if (mListItems.isEmpty()) {
noContentText.setText(R.string.no_images);
} else {
mImageAdapter.notifyDataSetChanged();
}
}
Although this does work to some extent, meaning that it manages to display the ViewPager when an item in the list is clicked, there are two things about it ringing the alarm bells:
I've read that calling setContentView() for the second time in the same class is pretty much a sin. Nobody explained me why.
The back button doesn't work in this case. When it's pressed, the application is terminated instead of going back to the list view. I believe this is connected to the first point.
I would appreciate any help, explanations if my idea is completely wrong, and if my case is hopeless, I'd like to see a successful combination of ListView and ViewPager with transitions between each other.
Your activity already has R.layout.activity_main set as content view, which rightly displays the list view - that's what the responsibility of this activity is as you defined it. If we want to change what's shown on the screen, we should use a different instance of a building block (activity or fragment) to display the view pager images.
To say the least, imagine if you wanted to change the view to a third piece of functionality or UI, or a fourth... it would be a nightmare to maintain, extend and test as you're not separating functionality into manageable units. Fields that are needed in one view are mixed with those needed in another, your class file would grow larger and larger as each view brings its click listeners, callbacks, etc., you'd also have to override the back button so it does what you want - it's just not how the Android framework was designed to help you. And what if you wanted to re-use UI components in different contexts whilst tapping in to the framework's activity lifecycle callbacks? That's why fragments were introduced.
In your case, the list view could continue to run in your MainActivity and in your click listener, onItemClick you could start a new activity that will hold a viewPager:
Intent i = new Intent(MainActivity.this, MyLargePhotoActivityPager.class);
i.putExtra(KEY_POSITION, position);
// pass the data too
startActivityForResult(i, REQUEST_CODE);
Notice how you could pass the position to this activity as an int extra, in order for that second activity to nicely set the viewPager to the position that the user clicked on. I'll let you discover how to build the second activity and put the ViewPager there. You also get back button functionality assuming your launch modes are set accordingly, if needed. One thing to note is that when you do come back to the list View, you'd probably want to scroll to the position from the view pager, which is why you could supply that back as a result via a request code. The returned position can be supplied back to the list view.
Alternatively, you could use the same activity but have two fragments (see the link further above) and have an equivalent outcome. In fact, one of your fragments could store the list view, and the second fragment could be a fullscreen DialogFragment that stores a viewPager, like a photo gallery (some details here).
Hope this helps.
I've read that calling setContentView() for the second time in the
same class is pretty much a sin. Nobody explained me why.
Well, you kind of get an idea as to why.
When you use setContentView() to display another 'screen' you do no have a proper back stack.
You also keep references to Views (like mListView) that are not visible anymore and are therefore kind of 'useless' after you setContentView() for the second time.
Also keep in mind orientation changes or your app going to the background - you'll have to keep track of the state that your Activity was in which is way more complicated than it has to be if you have one Activity that does two different things.
You won't be arrested for doing things like you do right now, but it's just harder to debug and keep bug free.
I'd suggest using two different Activities for the two different things that you want to do, or use one Activity and two Fragments, swapping them back and forth.
If you insist on having it all in one Activity you need to override onBackPressed() (called when the user presses the back button) and restore the first state of your Activity (setContentView() again, pretty much starting all over).

Android: Dynamically Change Activity Title to Text of Selected List Item

I'm new to Android development.
I created a simple master-detail app that starts with a simple, vertical scrolling list of topics.
When the user selects a topic, a details screen appears, replacing the first screen, with a list of details that pertain to the selected topic.
I want the title for the details screen to show the topic the user has selected on the first page, but haven't been able to solve the problem after working for almost a week.
All I need to know is, Can this be done? Not looking for someone to solve this for me, but maybe a hint or a link to a tutorial that shows how this can be done.
Note: I'd post a drawing of what I want to do, but I'm new here and don't have 10 reputation yet.
Thanks,
SonCoder
Not exactly sure what you want but either way..
-You have a listview. Each view (the data) in the listview should be a represented by a model. (aka a separate class containing specific information that you want to represent for each listitem.
-Write a custom list adapter (extend from base adapter).
http://www.androidhive.info/2012/02/android-custom-listview-with-image-and-text/
In the getView method of this class you load the the String field of the model that you want in the textview.
-Make sure to use the viewholder pattern in the adapter above. I noticed the example doesnt use one. This speeds up scrolling in the list because there are much fewer calls to findViewById.
-in the list activity set up a View onClick listener. This should create an intent (for launching an activity) or a fragment transaction (for fragments). Send the instance of your entire model (will get from
parent.getAdapter().getItem(position);
in the on click method) into the detail activity.
-if you want to set a textview title just get the textview and set it from the model. It will be the same filed you inflated in the getView method of the adapter.
-if you want to set the titile in the actionbar set:
this.getActionBar().setTitle(title)
This is simple. Just send extra data in the intent that starts the activity and then in the activity's onCreate read the data and then use the setTitle(myString) method from the activity.
setTitle(String title) can be called from anywhere using the activity by the way.
So, your in your listadapter, then you set a listener on your view right? A simple onClickListener on the whole "root" view is just fine.
In the listener you say something in the ways of this:
Intent intent = new Intent(myActivity, MySubActivity.class);
intent.putExtra(key, titleName);
myActivity.startActivity(intent);
Note that the activity reference should be set in the constructor of the adapter and that the "key" String is something you get from your strings.xml. Do not duplicate these in code since if you change one and forget to change the others you might get some wierd NPEs.
Continue in your MySubActivity's onCreate()
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = getIntent();
String key = getString(R.string.my_title_key);
String title = intent.getString(key);
setTitle(title);
}
NOTE: I'm not sure of all method names are correct and such but something like this.

How to make the back function and set the last contentView

I hawe many view's in my application and now the problem is how to go back from one view to another.
What I could do it by set back Buttons in every view but i would like to use the android back hard button.
I have tried something like this:
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if(keyCode==KeyEvent.KEYCODE_BACK)
{
finish();
}
return false;
}
But the problem is that this will close my application.
Could you please guide me for a proper solution, for example to memorize the last view was set and then to come back to this view or something like this.
Here is the code with which I am changing the view (it's a method in my main activity):
public void CheckIfUserIsLogedIn ()
{
int userPresence = localDatabase.CheckUserPresence();
if (userPresence == 0)
{
setContentView(R.layout.main);
}
else
{
setContentView(R.layout.userlogedon);
}
}
Thank you.
Look!
You are doing this wrong way..
An Activity class should only have on content View. (because it is recommended way and easy to use and implement).
And if you want to go to next View, show it under another separate Activity.
when you will finish it, you will be automatically redirected to previous Activity.
(and you don't need to memorize the Previous View :) )
See here, how to work with Activity Stacks.
I am not sure to understand your problem correctly because Android do all that for you automatically. Once a view is opened when you switch to another view it is paused (on screen but has not focus) or stopped (has no focus)
http://developer.android.com/reference/android/app/Activity.html
If the current view (activity) has been launched by the previous view (activity), pressing the back button will make you "close" the current view and go back to the previous one automatically.
Now two things :
Perhaps your are simply opening all views wihtin the same activity by showing on or off components which is a bad way of doing and is not recommended by android. What you should do is 1 view = 1 activity.
You are thinking like "iPhone/iPad" where you have to implements back buttons in the "views". In android you don't need to do so. Putting the "finish" command in your code at that point seem to close the application which make me think you have programmed as explained in point 1.
Hope it helps
EDIT:
To start a new activity do it like this
startActivity(new Intent(this, MyOtherActivity.class));
you put this in your code where you want to load the new view (activity)
Now if you want to transfer some information between activities you must do something like this :
Intent myIntent; //intent declaration
int aNumber = 10; // info to send to other activity
String aString = "abcd"; // info to send to other activity
// link Intent to the other activity
myIntent = new Intent(view.getContext(), MyOtherActivity.class)
//put the extra info
myIntent.putExtra("myNumber", aNumber);
myIntent.putExtra("myString", aString);
//start the new view/activity
startActivity(myIntent);
and in the new opened activity you retrieve the infos like this (in the oncreate usually)
int aNumber;
String aString;
#Override
public void onCreate(Bundle savedInstanceState) {
aNumber= getIntent().getExtras().getInt("myNumber");
aString= getIntent().getExtras().getString("myString");
}
Actually i m not sure that understand exactly but..
take a map or a shared preference and at the back button set last View on map or Shared preference .
At the calling or at start activity fetch the data which have stored you.
this will helps you.

Interpreting item click in ListView

I'm working on my first Android project, and I created a menu via the XML method. My activity is pretty basic, in that it loads the main layout (containing a ListView with my String array of options). Here's the code inside my Activity:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// allow stuff to happen when a list item is clicked
ListView ls = (ListView)findViewById(R.id.menu);
ls.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// #todo
}
});
}
Within the onItemClick callback handler, I'd like to check which item was clicked, and load a new menu based upon that.
Question 1: How do I go about figuring out which item was clicked? I can't find any straightforward examples on retrieving/testing the id value of the clicked item.
Question 2: Once I have the id value, I assume I can just call the setContentView method again to change to another layout containing my new menu. Is that correct?
I'm working on my first Android
project, and I created a menu via the
XML method.
Actually, Android has a separate concept of menus, so I'd be a bit wary about describing your UI in those terms.
How do I go about figuring out which
item was clicked?
If you are using an ArrayAdapter, the position parameter passed to onItemClick() is the index into your array.
I assume I can just call the
setContentView method again to change
to another layout containing my new
menu. Is that correct?
Yes, though there may be better approaches to the UI that will be more Android-y. Most Android applications do not start off with some sort of multi-layer navigation before you actually get to do something.

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