如何在GridView（Android）中交换图像

Question

我正在开发一个滑动拼图Android应用程序，所以我使用GridView来显示代表图块的16个图像。 其中一个图块将由纯白图像（代表背景）组成。 这个想法是，如果用户点击与白色瓷砖相邻的任何瓷砖，则所选瓷砖和白色瓷砖将切换位置。

我试图通过将白色图块设置为用户选择的图块来实现此功能，反之亦然。 我在变量masterTilePos中保存了白色瓷砖的位置（从位置15开始），并使用参考R.drawable文件中图像的ImageAdapter Integer数组，将masterValPos处的图像设置为所选索引处的图像，并将所选图像添加到白色图块。 但是，当我运行程序时，磁贴只能在第一次成功切换：之后，它无法正常工作，GridView中的磁贴顺序也会被破坏。 我想这可能是因为数组只是指实际的图像对象，但我不知道该怎么做呢？ 我遇到这个问题已经有三天了。 这是我的代码：

//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


  };

}

任何人都可以帮我解决这个问题，这样我就能成功切换网格中的图像吗？ 谢谢。

Answer 1

在onCreate你正在做：

gridview.setAdapter(new ImageAdapter(this));

因此，您创建了适配器，而没有将其分配给任何变量。 这是错的！

然后，每次交换你创建新的适配器：

ImageAdapter updater = new ImageAdapter(this);

并且您将其设置为当前适配器：

gridview.setAdapter(updater);

这也是错误的。

你必须这样做：

1. OnCreate - >创建适配器，将其分配给对象的变量（属性）
2. 然后你只需要使用那个变量。

然后，如果遇到问题，请在SWAP方法中调试逻辑。

    //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
  };
}