單擊另一個單元格時如何更改GridView單元格的圖像？

Question

我希望圖像只出現在一個地方。當單擊另一個單元格時，同一圖像將出現在那裏，並從先前單擊的按鈕中消失。

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 
       imageView = new ImageView(mContext); 
       imageView.setLayoutParams(new GridView.LayoutParams(85, 85)); 

       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. Here are 16 for 4x4 grid 
    private Integer[] mThumbIds = { 
      R.drawable.sample_2, R.drawable.sample_3, 
      R.drawable.sample_4, R.drawable.sample_5, 
      R.drawable.sample_6, R.drawable.sample_7, 
      R.drawable.sample_0, R.drawable.sample_1, 
      R.drawable.sample_2, R.drawable.sample_3, 
      R.drawable.sample_4, R.drawable.sample_5, 
      R.drawable.sample_6, R.drawable.sample_7, 
      R.drawable.sample_0, R.drawable.sample_1, 

    }; 

} 

MainActivity.java

public class MainActivity extends Activity { 

    int i=0; 
    long firstClick,secondClick; 


    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     //no title 
     requestWindowFeature(Window.FEATURE_NO_TITLE); 
     // making it full screen 
     getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); 
     setContentView(R.layout.activity_main); 


     GridView gridview = (GridView) findViewById(R.id.gridview); 

     gridview.setAdapter(new ImageAdapter(this)); 



     gridview.setOnItemClickListener(new OnItemClickListener(){ 

      @Override 
      public void onItemClick(AdapterView<?> parent, View v, int position, 
        long id) { 
       // TODO Auto-generated method stub 

       ImageView imageView = (ImageView) v; 
        imageView.setImageResource(R.drawable.sample_8); 
      } 
     }); 
    }  
} 

Answer 1

不要修改從GridView直接ImageView，而不是從適配器修改數據，並調用notifyDataSetChanged。

@Override 
    public void onItemClick(AdapterView<?> parent, View v, int position, 
      long id) { 
     if (lastClicked != -1) { 
       // we previously selected a position 
       mThumbs[lastClicked] = R.drawable.default_image;     
     } 
     if (lastClicked != position) { 
       mThumbs[position] = R.drawable.image_required_when_grid_selected; 
     } 
     lastClicked = position; 
     mAdapter.notifyDataSetChanged(); // mAdapter is a reference to the GridView's adapter 
    } 

lastClicked會在你的類中的字段存儲了最後一次點擊的位置：

int lastClicked = -1; // -1 meaning there were no selection