java - 如何在 GridView 中交换图像 (Android)

Question

我正在开发一个 slider 拼图 Android 应用程序，因此我使用 GridView 来显示 16 个代表图 block 的图像。其中一个图 block 将由纯白色图像(代表背景)组成。这个想法是，如果用户单击与白色瓷砖相邻的任何瓷砖，则所选瓷砖和白色瓷砖将交换位置。

我试图通过将白色图 block 设置为用户选择的图 block 来实现这一点，反之亦然。我将白色图 block 的位置(它从位置 15 开始)保存在变量 masterTilePos 中，并使用 ImageAdapter Integer 数组引用我的 R.drawable 文件中的图像，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 block 。但是，当我运行该程序时，图 block 仅在第一次成功切换:之后，它无法正常工作并且 GridView 中图 block 的顺序被破坏。我认为这可能是因为数组只是指实际的图像对象，但我不确定该怎么做；我遇到这个问题已经三天了。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，以便我可以在网格内成功切换图像吗？谢谢。

Answer 1

在 onCreate 中你正在做:

gridview.setAdapter(new ImageAdapter(this));

因此，您创建了适配器，但没有将其分配给任何变量。这是错误的!

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. 然后您只需要使用该变量。

然后，如果您遇到问题，请在 SWAP 方法中调试您的逻辑。

    //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
  };
}