title: Change Color of gridview cell on click
body: <p>I have a gridview that contains text and images. When a user touches a cell in the grid, it changes color to show that it is selected and when selected again it returns to the default color to show that it is no longer selected. Any number of cells can be selected. The problem is when a user has to scroll through the grid to see all of the icons the selected icons sometimes become unselected and select "random" other cells. 
  I suspect this is related to the gridview being recycled but am unsure how to address this. </p>
  
  <pre><code>public class Onboarding extends Activity {
  GridView grid;
  ArrayList selectedCategories = new ArrayList&lt;&gt;();
  CustomGrid adapter;
  String[] dummyString = {
          "item 1",
          "item 2",
          "item 3",
          "item 4",
          "item 5",
          "item 6",
          "item 7",
          "item 8",
          "item 9",
          "item 10",
          "item 11",
          "item 12",
          "item 13",
          "item 14",
          "item 15",
          "item 16",
          "item 17",
          "item 18",
          "item 19"
  };
  int[] imageId = {
          R.drawable.1,
          R.drawable.2,
          R.drawable.3,
          R.drawable.4,
          R.drawable.5,
          R.drawable.6,
          R.drawable.7,
          R.drawable.8,
          R.drawable.9,
          R.drawable.10,
          R.drawable.11,
          R.drawable.12,
          R.drawable.13,
          R.drawable.14,
          R.drawable.15,
          R.drawable.16,
          R.drawable.17,
          R.drawable.18,
          R.drawable.19
  };
  
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_onboarding);
      getWindow().setSoftInputMode(
              WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN
      ); //makes sure keyboard is hidden on this view as it is not needed
      setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT);
  
      grid = (GridView) findViewById(R.id.grid);
  
      //deals with settings the number of Columns
      DisplayMetrics displayMetrics = this.getResources().getDisplayMetrics();
      double dpWidth = displayMetrics.widthPixels / displayMetrics.density;
      if (dpWidth &lt;= 400) {
          grid.setNumColumns(2);
      } else if (dpWidth &gt; 400 &amp;&amp; dpWidth &lt; 500) {
          grid.setNumColumns(3);
      } else if (dpWidth &gt;= 500 &amp;&amp; dpWidth &lt; 550) {
          grid.setNumColumns(4);
      } else {
          grid.setNumColumns(5);
      }
  
      adapter = new CustomGrid(Onboarding.this, dummyString, imageId);
      grid.setAdapter(adapter);
      grid.setOnItemClickListener(new AdapterView.OnItemClickListener() {
          @Override
          public void onItemClick(AdapterView&lt;?&gt; parent, View view,
                                  int position, long id) {
              //the position is the actual position that is pressed. but the getChildAt returns gets the relative position, ie what's being drawn
              //on the grid.
              //to fix this, the first visible position is obtained and the difference is subtracted
              int firstPos = grid.getFirstVisiblePosition();
              View tv = grid.getChildAt(position - firstPos);
              Toast.makeText(Onboarding.this, "You Clicked at position" + position + " " + dummyString[+position] + "firstPos " + firstPos, Toast.LENGTH_SHORT).show(); //debug
  
              if (tv == null) { //this shouldn't/doesn't happen
                  Log.e("OnBoarding.java", "Issue with null view at line " + Thread.currentThread().getStackTrace()[2].getLineNumber() +
                          "grid is having a problem");
                  return;
              }
  
              if (selectedCategories.contains(dummyString[+position]) == false) {//add the item if it doesn't exist
                  selectedCategories.add(dummyString[+position]);
                  tv.setBackgroundColor(Color.parseColor("#FFE5CD"));
              } else { //remove the item if it already exists, as the user is removing it by touching it again
                  selectedCategories.remove(dummyString[+position]);
                  tv.setBackgroundColor(Color.parseColor("#EEEEEE"));
              }
          }
      });
  
  }
  </code></pre>
  
  <p>}</p>
  
  <pre><code>public class CustomGrid extends BaseAdapter {
  private Context mContext;
  private final String[] genreString;
  private final int[] Imageid;
  
  public CustomGrid(Context c, String[] genreString, int[] Imageid) {
      mContext = c;
      this.Imageid = Imageid;
      this.genreString = genreString;
  }
  
  @Override
  public int getCount() {
      return genreString.length;
  }
  
  @Override
  public Object getItem(int position) {
      return null;
  }
  
  @Override
  public long getItemId(int position) {
      return 0;
  }
  
  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
      View grid;
      LayoutInflater inflater = (LayoutInflater) mContext
              .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
      TextView textView;
      ImageView imageView;
      if (convertView == null) {
          grid = inflater.inflate(R.layout.grid_single, null);
      } else {
          grid = convertView;
      }
      textView  = (TextView) grid.findViewById(R.id.grid_text);
      imageView = (ImageView) grid.findViewById(R.id.grid_image);
      textView.setText(genreString[position]);
      imageView.setImageResource(Imageid[position]);
  
      return grid;
  }
  </code></pre>
  
  <p>}</p>