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Disable Scroll left in ViewPager Android Studio

I know this is common to ask but still I'm confused how can I disable scroll to left from ViewPager, What I'm trying to do is when the input field/household field is empty you cannot procced to the next part, currently it works on the button when I'm trying to click next button it will pops Toast, but when I scroll using my finger it didn't work since I didn't applied it yet, can anyone explain or how can I achieve this? I'm struggling with this one.
OnBoardingScreen - Java
private TextView tvNext, tvSkip;
private ViewPager viewPager;
private LinearLayout layoutDots;
private IntroPref introPref;
private int[] layouts;
private TextView[] dots;
private MyViewPagerAdapter viewPagerAdapter;
EditText edt_hh;
tvNext.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
edt_hh = findViewById(R.id.edt_hh_no);
household = edt_hh.getText().toString();
int current = getItem(+1);
//
if (household.matches("")){
Toasty.error(getApplicationContext(),"Required", Toasty.LENGTH_SHORT).show();
}
else if (current < layouts.length) {
viewPager.setCurrentItem(current);
}
else {
launchHomeScreen();
}
}
});
ViewPager.OnPageChangeListener onPageChangeListener = new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
addBottomDots(position);
edt_hh = findViewById(R.id.edt_hh_no);
household = edt_hh.getText().toString();
if (household.matches("")){
Toasty.error(getApplicationContext(),"Required", Toasty.LENGTH_SHORT).show();
}
else if (position == layouts.length - 1) {
tvNext.setText("SCAN");
} else {
tvNext.setText("NEXT");
}
}
#Override
public void onPageScrollStateChanged(int state) {
}
};
private void addBottomDots(int currentPage) {
dots = new TextView[layouts.length];
int[] activeColors = getResources().getIntArray(R.array.active);
int[] inActiveColors = getResources().getIntArray(R.array.inactive);
layoutDots.removeAllViews();
for (int i = 0; i < dots.length; i++) {
dots[i] = new TextView(this);
dots[i].setText(Html.fromHtml("&#8226"));
dots[i].setTextSize(50);
dots[i].setTextColor(inActiveColors[currentPage]);
layoutDots.addView(dots[i]);
}
if (dots.length > 0) {
dots[currentPage].setTextColor(activeColors[currentPage]);
}
}
public class MyViewPagerAdapter extends PagerAdapter {
LayoutInflater layoutInflater;
public MyViewPagerAdapter() {
}
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, int position) {
layoutInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = layoutInflater.inflate(layouts[position], container, false);
container.addView(view);
return view;
}
#Override
public int getCount() {
return layouts.length;
}
#Override
public boolean isViewFromObject(#NonNull View view, #NonNull Object object) {
return view == object;
}
#Override
public void destroyItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
View view = (View) object;
container.removeView(view);
}
}
private int getItem(int i) {
return viewPager.getCurrentItem() + 1;
}
private void launchHomeScreen() {
showImageImportDialog();
}
private void changeStatusBarColor() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
Window window = getWindow();
window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
window.setStatusBarColor(Color.TRANSPARENT);
}
}
xml
<androidx.viewpager.widget.ViewPager
android:id="#+id/viewPager"
android:layout_width="match_parent"
android:layout_height="match_parent" />

Now it is possible to enable-disable swiping viewpager2
https://developer.android.com/guide/navigation/navigation-swipe-view-2
Note: If your app already uses ViewPager, see Migrate from ViewPager to ViewPager2.
Sample code to disable swiping in viewpager2
myViewPager2.setUserInputEnabled(false);
Sample code to enable swiping in viewpager2
myViewPager2.setUserInputEnabled(true);

You can disable your view pager scroll using custom ViewPager :
Is it possible to disable scrolling on a ViewPager

At what point can I get the width of a view in a RecyclerView?

I am using recycler. I need to set height of the view as the width of the container. But the problem is when I am trying to get the width size it seems not exist yet so it returns zero. How I can make sure that view is already created to get its value and use it while setting the height?
That is the code where i am setting the height
imageView.getLayoutParams().height = container.getWidth();
imageView.requestLayout();
The code of the adapter
public class OnlineUsersAdapter extends RecyclerView.Adapter<OnlineUsersAdapter.OnlineUserViewHolder> {
private List<OnlineUser> onlineUsers = new ArrayList<>();
private OnItemClickListener.OnItemClickCallback onItemClickCallback;
private OnItemClickListener.OnItemClickCallback onChatClickCallback;
private OnItemClickListener.OnItemClickCallback onLikeClickCallback;
private Context context;
public OnlineUsersAdapter(OnItemClickListener.OnItemClickCallback onItemClickCallback,
OnItemClickListener.OnItemClickCallback onChatClickCallback,
OnItemClickListener.OnItemClickCallback onLikeClickCallback) {
this.onItemClickCallback = onItemClickCallback;
this.onChatClickCallback = onChatClickCallback;
this.onLikeClickCallback = onLikeClickCallback;
}
public void addUsers(List<OnlineUser> userList) {
onlineUsers.addAll(userList);
notifyItemRangeInserted(onlineUsers.size() - userList.size(), onlineUsers.size());
}
public void clearData(List<OnlineUser> userList){
int oldSize = userList.size();
onlineUsers = userList;
notifyItemRangeRemoved(0, oldSize);
notifyItemRangeInserted(0, userList.size());
}
#NonNull
#Override
public OnlineUsersAdapter.OnlineUserViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
context = parent.getContext();
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_user, parent, false);
return new OnlineUsersAdapter.OnlineUserViewHolder(v);
}
#Override
public void onBindViewHolder(#NonNull OnlineUsersAdapter.OnlineUserViewHolder holder, int position) {
OnlineUser user = onlineUsers.get(position);
holder.bind(user, position);
}
#Override
public int getItemCount() {
return onlineUsers.size();
}
class OnlineUserViewHolder extends RecyclerView.ViewHolder {
RelativeLayout container;
ImageView imageView, likeBtn, chatBtn;
TextView name, country;
private LottieAnimationView animationView;
OnlineUserViewHolder(View itemView) {
super(itemView);
context = itemView.getContext();
container = itemView.findViewById(R.id.item_user_container);
imageView = itemView.findViewById(R.id.user_img);
likeBtn = itemView.findViewById(R.id.search_btn_like);
chatBtn = itemView.findViewById(R.id.search_btn_chat);
name = itemView.findViewById(R.id.user_name);
country = itemView.findViewById(R.id.user_country);
animationView = itemView.findViewById(R.id.lottieAnimationView);
}
void bind(OnlineUser user, int position) {
ViewCompat.setTransitionName(imageView, user.getName());
if (FirebaseUtils.isUserExist() && user.getUid() != null) {
new FriendRepository().isLiked(user.getUid(), flag -> {
if (flag) {
likeBtn.setBackground(ContextCompat.getDrawable(context, R.drawable.ic_favorite));
animationView.setVisibility(View.VISIBLE);
} else {
likeBtn.setBackground(ContextCompat.getDrawable(context, R.drawable.heart_outline));
animationView.setVisibility(View.GONE);
}
});
}
if (user.getUid() != null) {
chatBtn.setOnClickListener(new OnItemClickListener(position, onChatClickCallback));
likeBtn.setOnClickListener(new OnItemClickListener(position, onLikeClickCallback));
}
imageView.setOnClickListener(new OnItemClickListener(position, onItemClickCallback));
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
if (user.getImage().equals(Consts.DEFAULT)) {
Glide.with(context).load(context.getResources().getDrawable(R.drawable.default_avatar)).into(imageView);
} else {
Glide.with(context).load(user.getImage()).thumbnail(0.5f).into(imageView);
}
country.setText(user.getCountry());
ValueAnimator animator = ValueAnimator.ofFloat(0f, 1f).setDuration(500);
animator.addUpdateListener(valueAnimator ->
animationView.setProgress((Float) valueAnimator.getAnimatedValue()));
if (animationView.getProgress() == 0f) {
animator.start();
} else {
animationView.setProgress(0f);
}
imageView.getLayoutParams().height = 500;
imageView.requestLayout();
}
}
}

Wait until your view gets rendered on UI. There are a few ways to do that. One of them is to use post() of the view which you want to get the height.
Like
container.post(new Runnable() {
#Override
public void run() {
imageView.getLayoutParams().height = container.getWidth();
imageView.requestLayout();
}
});
And View's getWidth() and getHeight() returns 0 is an amazing post which contains few Kotlin solutions too, which are more easier than Java.

parent.getMeasuredWidth() and parent.getMeasuredHeight() return 0 in ImageAdapter for GridView

I have 6 drawable images. I put this images in a GridView in 2x3 if it's portraite and 3x2 if it's landscape, but i have a problem: if i try to put measures based on parent.getMeasuredWidth() and parent.getMeasuredHeight();
first drawable have always 0 as width and hight;
From LOG:
w: 0 h:0
Code ImageAdapter:
public class ImageAdapter extends BaseAdapter {
private Context mContext;
public ImageAdapter(Context c) {mContext = c;}
public int getCount() {return mThumbIds.length;}
public Object getItem(int position) {return null;}
public long getItemId(int position) {return 0;}
public View getView(int position, View convertView, final ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
int width = parent.getMeasuredWidth();
int height = parent.getMeasuredHeight();
int orientation = parent.getResources().getConfiguration().orientation;
int vh,vo;
if(orientation == 1){
vh = width/2;
vo = height/3;
} else {
vh = (width/3);
vo = (height/2);
}
Log.e(TAG,"w: "+vh+" h:"+vo);
imageView = new ImageView(mContext);
imageView.setLayoutParams(new GridView.LayoutParams(vh, vo));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setPadding(0, 0, 0, 0);
} else {
imageView = (ImageView) convertView;
}
imageView.setImageResource(mThumbIds[position]);
return imageView;
}
// references to our images
private Integer[] mThumbIds = {
R.drawable.gradient_bg_t1,
R.drawable.gradient_bg_t2,
R.drawable.gradient_bg_t4,
R.drawable.gradient_bg_t5,
R.drawable.gradient_bg_t6,
R.drawable.gradient_bg_t3
};
}
Code MainActivity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.my_layout);
gridview = (GridView) findViewById(R.id.gridview);
gridview.setAdapter(new ImageAdapter(this));
gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
}
});
}
Thank you.

it returns zero because the parent view isnt drawn yet. you can post your code to the parent view so it runs after parent view was drawn.
use below code:
parent.post(new Runnable() {
#Override
public void run() {
int w = parent.getMeasuredWidth();
int h = parent.getMeasuredHeight();
...
}
});

I already tried the code of #Amir Ziarati in ImageAdapter (found it in StackOverflow), but i can't get the values out of scope.
After i drink a little coffee i changed the code a litle:
I created in ImageAdapter 2 new int variable w,h for width and height:
private Context mContext;
private int w,h;
public ImageAdapter(Context c,int width,int height) {
mContext = c;
w = width;
h = height;
}
and in MainActivity:
gridview = (GridView) findViewById(R.id.gridview);
gridview.post(new Runnable() {
#Override
public void run() {
int w = gridview.getMeasuredWidth();
int h = gridview.getMeasuredHeight();
gridview.setAdapter(new ImageAdapter(MainActivity.this,w,h));
}
});
gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
}
});
And it's working.

Background color or Images shuffling on scrolling in recyclerview?

I am wondering that my images and color of layouts shuffling when i scrolls downwards or upwards, I created cardview using recyclerview. and set an image(changes color on click like to know if its user's favourite item) and setbackgroundcolor(randomly chossen) to the parent layout to make cardview attractive. but when i scrolls
1. the image that image changes position,
2. the layout background changes color automatically.
I am posting my adapter's code here.
public class TOAdapter extends RecyclerView.Adapter<TOAdapter.ViewHolder> {
JSONArray jsonArray;
private String title;
private String image;
private ImageLoader imageLoader;
private String subtitle;
private String subti;
private Context context;
private ImageView clip;
public TOAdapter(JSONArray jsonArray) {
this.jsonArray = jsonArray;
}
// Create new views (invoked by the layout manager)
#Override
public TOAdapter.ViewHolder onCreateViewHolder(final ViewGroup parent,
int viewType) {
// create a new view
View itemLayoutView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.top_twenty_list, parent, false);
final ViewHolder viewHolder = new ViewHolder(itemLayoutView);
final Random random = new Random(System.currentTimeMillis());// We add 155 since we want at least 155 in each channel.// Then we add to it a random number between 0 and 100.
int r = 155 + random.nextInt(101);
int g = 155 + random.nextInt(101);
int b = 155 + random.nextInt(101);
int color = Color.rgb(r, g, b);
viewHolder.frame.setBackgroundColor(color);
viewHolder.layer.setBackgroundColor(color);
clip = (ImageView) itemLayoutView.findViewById(R.id.ic_clip);
clip.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
int iColor = Color.parseColor("#0000FF");
int red = (iColor & 0xFF0000) / 0xFFFF;
int green = (iColor & 0xFF00) / 0xFF;
int blue = iColor & 0xFF;
float[] matrix = {0, 0, 0, 0, red
, 0, 0, 0, 0, green
, 0, 0, 0, 0, blue
, 0, 0, 0, 1, 0};
ColorFilter colorFilter = new ColorMatrixColorFilter(matrix);
clip.setColorFilter(colorFilter);
}
});
return viewHolder;
}
// Replace the contents of a view (invoked by the layout manager)
#Override
public void onBindViewHolder(final ViewHolder viewHolder, int position) {
// - get data from your itemsData at this position
// - replace the contents of the view with that itemsData
// myTypeface = Typeface.createFromAsset(context.getAssets(), "fonts/RobotoCondensedBoldItalic.ttf");
try {
JSONObject obj = jsonArray.getJSONObject(position);
title = obj.getString("title");
image = obj.getString("brand_logo");
subtitle = obj.getString("sub_title");
} catch (JSONException e) {
e.printStackTrace();
}
viewHolder.txtViewTitle.setText(subtitle);
viewHolder.subtitle.setText(title);
if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
String full_Url = "http://mycompany/assets/new" + image;
viewHolder.thumbnail.setImageUrl(full_Url, imageLoader);
viewHolder.btn_get_deal.setTag(position);
viewHolder.btn_get_deal.setOnClickListener(new View.OnClickListener() {
public JSONObject obj;
public ArrayList<String> offerlist = new ArrayList();
#Override
public void onClick(View view) {
Intent offerpage = new Intent(AppController.getInstance().getApplicationContext(), OfferDetails.class);
Integer pos = (Integer) view.getTag();
try {
obj = jsonArray.getJSONObject(pos);
offerpage.putExtra("jsonObj", obj.toString());
} catch (JSONException e) {
e.printStackTrace();
}
//offerpage.getParcelableArrayListExtra(offerlist);
offerpage.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
AppController.getInstance().getApplicationContext().startActivity(offerpage);
}
});
//viewHolder.txtViewTitle.setTypeface(myTypeface);
}
// inner class to hold a reference to each item of RecyclerView
public static class ViewHolder extends RecyclerView.ViewHolder {
private final NetworkImageView thumbnail;
private final RelativeLayout frame;
private final RelativeLayout layer;
public TextView txtViewTitle;
public TextView subtitle;
public ImageView clip;
public CardView btn_get_deal;
public ViewHolder(View itemLayoutView) {
super(itemLayoutView);
txtViewTitle = (TextView) itemLayoutView.findViewById(R.id.txttitle_toptwenty);
subtitle = (TextView) itemLayoutView.findViewById(R.id.sub_title_toptwenty);
thumbnail = (NetworkImageView) itemLayoutView.findViewById(R.id.thumbnail_topwenty);
frame = (RelativeLayout) itemLayoutView.findViewById(R.id.frame);
layer = (RelativeLayout) itemLayoutView.findViewById(R.id.layer);
btn_get_deal = (CardView) itemLayoutView.findViewById(R.id.card_view);
}
}
// Return the size of your itemsData (invoked by the layout manager)
#Override
public int getItemCount() {
return jsonArray.length();
}
}

I have created a working example of what you are trying to accomplish. The source of the errors you experience is mostly that you don't understand view recycling. I am not going to explain the whole thing to you now, but anyway here is the example:
For the example I used this layout for each row:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
android:id="#+id/background"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="80dp">
<TextView
android:id="#+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"/>
</FrameLayout>
I used this model:
public class ExampleModel {
private final int mColor;
private final String mText;
public ExampleModel(int color, String text) {
mColor = color;
mText = text;
}
public int getColor() {
return mColor;
}
public String getText() {
return mText;
}
}
And this view holder:
public class ExampleViewHolder extends RecyclerView.ViewHolder {
private final FrameLayout mBackground;
private final TextView mTextView;
public ExampleViewHolder(View itemView) {
super(itemView);
mBackground = (FrameLayout) itemView.findViewById(R.id.background);
mTextView = (TextView) itemView.findViewById(R.id.textView);
}
public void bind(ExampleModel model) {
mBackground.setBackgroundColor(model.getColor());
mTextView.setText(model.getText());
}
}
As you can see nothing special, the Adapter implementation is equally simple:
public class ExampleAdapter extends RecyclerView.Adapter<ExampleViewHolder> {
private final LayoutInflater mInflater;
private final List<ExampleModel> mModels;
public ExampleAdapter(Context context, List<ExampleModel> models) {
mInflater = LayoutInflater.from(context);
mModels = models;
}
#Override
public ExampleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
final View itemView = mInflater.inflate(R.layout.item_example, parent, false);
return new ExampleViewHolder(itemView);
}
#Override
public void onBindViewHolder(ExampleViewHolder holder, int position) {
final ExampleModel model = mModels.get(position);
holder.bind(model);
}
#Override
public int getItemCount() {
return mModels.size();
}
}
And you use the whole thing like this:
final Random mRandom = new Random(System.currentTimeMillis());
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
final List<ExampleModel> models = new ArrayList<>();
for (int i = 0; i < 100; i++) {
final int randomColor = generateRandomPastelColor();
models.add(new ExampleModel(randomColor, String.valueOf(i)));
}
final ExampleAdapter adapter = new ExampleAdapter(getActivity(), models);
recyclerView.setAdapter(adapter);
}
public int generateRandomPastelColor() {
final int baseColor = Color.WHITE;
final int red = (Color.red(baseColor) + mRandom.nextInt(256)) / 2;
final int green = (Color.green(baseColor) + mRandom.nextInt(256)) / 2;
final int blue = (Color.blue(baseColor) + mRandom.nextInt(256)) / 2;
return Color.rgb(red, green, blue);
}
This should do what you are looking for and you can use it as an example of how to implement your Adapter.

I got the same problem ,when i used the radioButton in my listView row, I solved it. As in every scrolling the Cache is cleared, you have to store the changed data in every row. just check my code
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
// if(position==0)
// Toast.makeText(context, ""+QuestionViewPageAdapter.mRadioGroupData, Toast.LENGTH_SHORT).show();
final ViewHolder viewHolder;
View row=convertView;
radioButton=new RadioButton[Integer.parseInt(mNoOfCategoryGreading)];
LayoutInflater inflater =LayoutInflater.from(context);//(LayoutInflater)context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(R.layout.question_row, parent, false);
viewHolder=new ViewHolder();
viewHolder.tv_qContent=(TextView)row.findViewById(R.id.tv_question);
viewHolder.rg=(RadioGroup)row.findViewById(R.id.rgrp);
for(int i=0;i<Integer.parseInt(mNoOfCategoryGreading);i++)
{
radioButton[i]=new RadioButton(context);
radioButton[i].setLayoutParams(new RadioGroup.LayoutParams(0, LayoutParams.WRAP_CONTENT,1f));
//1f for layout_weight="1"
radioButton[i].setId(i);
radioButton[i].setText(""+(i+1));
viewHolder.rg.addView(radioButton[i]);
}
row.setTag(viewHolder);
for(int i=0;i<QuestionViewPageAdapter.mRadioGroupData.size();i++){
int p=Integer.parseInt(""+QuestionViewPageAdapter.mRadioGroupData.get(i).get("position"));
String id=QuestionViewPageAdapter.mRadioGroupData.get(i).get("Id");
if(p!=-1 && id.equals(""+data.get(position).get(AppData.question_Set_category_QuestionID)))
{//radioButton[p].setSelected(true);
viewHolder.rg.check(p-1);}
//Toast.makeText(context, "Yes "+p, Toast.LENGTH_LONG).show();}
}
viewHolder.tv_qContent.setText((position+1)+". "+data.get(position).get(AppData.question_Set_category_QuestionContent));
viewHolder.tv_qContent.setTypeface(typeface_muso_regular300);
viewHolder.rg.setOnCheckedChangeListener(new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
// TODO Auto-generated method stub
String s=data.get(position).get(AppData.question_Set_category_QuestionID);
isAvailabel(s);
int radioButtonID = viewHolder.rg.getCheckedRadioButtonId();
View radioButton = viewHolder.rg.findViewById(radioButtonID);
int idx = viewHolder.rg.indexOfChild(radioButton);
HashMap<String, String> map=new HashMap<String, String>();
map.put("position", ""+(idx+1));
map.put("Id", ""+data.get(position).get(AppData.question_Set_category_QuestionID));
map.put("CategoryId", ""+mCategoryId);
QuestionViewPageAdapter.mRadioGroupData.add(map);
}
});
return row;
}
private void isAvailabel(String qId){
for(int i=0;i<QuestionViewPageAdapter.mRadioGroupData.size();i++){
if(qId.equals(QuestionViewPageAdapter.mRadioGroupData.get(i).get("Id"))){
position=i;
QuestionViewPageAdapter.mRadioGroupData.remove(i);
}
}
}
class ViewHolder {
TextView tv_qContent ,tv_1,tv_2,tv_3;
RadioGroup rg;
RadioButton rBtn1,rBtn2,rBtn3,rBtn4,rBtn5;
}

After days of struggle and headache, i have found a very simple solution.
In your adapter you just need to override 2 methods.
#Override
public int getItemViewType(int position) {
return position;
}
#Override
public long getItemId(int position) {
return position;
}
Helped me resolve the shuffling issue of recycler view.

In my case overriding getItemId and setting sethasStableIds to true solved the shuffling issue.
in adapter:
#Override
public long getItemId(int position) {
Object listItem = feeds.get(position);
return listItem.hashCode();
}
in main activity/fragment :
adapter = new FeedAdapter(feeds, getContext());
adapter.setHasStableIds(true);

How to swap images in a GridView (Android)

I'm working on a slider puzzle Android app, so I'm using a GridView to display 16 images representing tiles. One of the tiles will consist of a plain white image (representing the background). The idea is that if the user clicks on any tile neighboring the white tile, the selected tile and the white tile will switch positions.
I'm trying to implement this by setting the white tile to the tile selected by the user, and vice versa. I saved the position of the white tile (it starts off at position 15) in the variable masterTilePos, and using the ImageAdapter Integer array referring to the images in my R.drawable file, set the image at masterValPos to the image at the selected index, and the selected image to the white tile. However, when I run the program, the tiles only successfully switch the first time: after that, it doesn't work properly and the order of the tiles within the GridView is ruined. I think it may because the array is simply referring to the actual image objects, but I'm not sure how to what to do instead; it has already been three days since I ran into this problem. Here is my code:
//GRID VIEW
public class MainActivity extends ActionBarActivity {
int masterTilePos = 15;
GridView gridview;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
gridview = (GridView) findViewById(R.id.gridview);
gridview.setAdapter(new ImageAdapter(this));
gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
//These methods check if a neighboring tile is white, if there is one, swap() is called
if(checkUp(position) || checkDown(position) || checkLeft(position) || checkRight(position)) {
swap(position);
}
}
});
}
public void swap(int pos) {
ImageAdapter updater = new ImageAdapter(this);
//This is where I try to switch the images, and seems to be the source of the problem
int val = updater.mThumbIds[masterTilePos];
updater.mThumbIds[masterTilePos] = updater.mThumbIds[pos];
updater.mThumbIds[pos] = val;
updater.notifyDataSetChanged();
gridview.setAdapter(updater);
gridview.invalidateViews();
masterTilePos = pos;
}
}
//IMAGE ADAPTER
public class ImageAdapter extends BaseAdapter {
private Context mContext;
public ImageAdapter(Context c) {
mContext = c;
}
public int getCount() {
return mThumbIds.length;
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
// if it's not recycled, initialize some attributes
DisplayMetrics metrics = mContext.getResources().getDisplayMetrics();
int width = metrics.widthPixels / 4;
int height = metrics.heightPixels / 4;
imageView = new ImageView(mContext);
imageView.setLayoutParams(new GridView.LayoutParams(width, height));
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
imageView.setPadding(1, 1, 1, 1);
}
else {
imageView = (ImageView) convertView;
}
imageView.setImageResource(mThumbIds[position]);
return imageView;
}
// the array containing references to the images
public Integer[] mThumbIds = {
R.drawable.pic1,
R.drawable.pic2,
R.drawable.pic3,
R.drawable.pic4,
R.drawable.pic5,
R.drawable.pic6,
R.drawable.pic7,
R.drawable.pic8,
R.drawable.pic9,
R.drawable.pic10,
R.drawable.pic11,
R.drawable.pic12,
R.drawable.pic13,
R.drawable.pic14,
R.drawable.pic15,
R.drawable.background
};
}
Can anyone please help me solve this so I can successfully switch the images within the grid? Thanks.

In onCreate you are doing:
gridview.setAdapter(new ImageAdapter(this));
So, you created adapter, without assign it to any variable. This is wrong!
Then, every swap you create new Adapter:
ImageAdapter updater = new ImageAdapter(this);
And you are setting it as current adapter:
gridview.setAdapter(updater);
This is wrong as well.
You must do in such a way:
OnCreate -> create adapter, assign it to objects's variable (property)
Then you need to work only with that variable.
And then, if you have a problem, debug your logic in SWAP method.
//GRID VIEW
public class MainActivity extends ActionBarActivity {
int masterTilePos = 15;
GridView gridview;
ImageAdapter imageAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
gridview = (GridView) findViewById(R.id.gridview);
imageAdapter= new ImageAdapter(this);
gridview.setAdapter(imageAdapter);
gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
//These methods check if a neighboring tile is white, if there is one, swap() is called
if(checkUp(position) || checkDown(position) || checkLeft(position) || checkRight(position)) {
swap(position);
}
}
});
}
public void swap(int pos) {
//This is where I try to switch the images, and seems to be the source of the problem
int val = imageAdaptor.mThumbIds[masterTilePos];
imageAdapter.mThumbIds[masterTilePos] = imageAdapter.mThumbIds[pos];
imageAdapter.mThumbIds[pos] = val;
imageAdapter.notifyDataSetChanged();
gridview.invalidateViews();
masterTilePos = pos;
}
}
//IMAGE ADAPTER
public class ImageAdapter extends BaseAdapter {
private Context mContext;
public ImageAdapter(Context c) {
mContext = c;
}
public int getCount() {
return mThumbIds.length;
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
// if it's not recycled, initialize some attributes
DisplayMetrics metrics = mContext.getResources().getDisplayMetrics();
int width = metrics.widthPixels / 4;
int height = metrics.heightPixels / 4;
imageView = new ImageView(mContext);
imageView.setLayoutParams(new GridView.LayoutParams(width, height));
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
imageView.setPadding(1, 1, 1, 1);
}
else {
imageView = (ImageView) convertView;
}
imageView.setImageResource(mThumbIds[position]);
return imageView;
}
// the array containing references to the images
public Integer[] mThumbIds = {
R.drawable.pic1,
R.drawable.pic2,
R.drawable.pic3,
R.drawable.pic4,
R.drawable.pic5,
R.drawable.pic6,
R.drawable.pic7,
R.drawable.pic8,
R.drawable.pic9,
R.drawable.pic10,
R.drawable.pic11,
R.drawable.pic12,
R.drawable.pic13,
R.drawable.pic14,
R.drawable.pic15,
R.drawable.background
};
}