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Android application crashes when showing multiple images in GridView component

由 假如想象 提交于 2019-12-05 22:51:35

Your problem arises due to the exhaustion of the heap size while allocating drawable resources (it is a common problem, since lots of memory required for this kind of operation).

When i have tried your code, i got java.lang.OutOfMemoryError: bitmap size exceeds VM budget . Which is a straightforward self-explanatory error message.

Then i made some research and came across a 'native' thread on official Android Dev website: http://developer.android.com/training/displaying-bitmaps/index.html about Bitmaps and examples on how to make efficient resource allocations in applications.

So I tried it and combined with your code and this is what i got:

ImageAdapter.java :

package com.humanoid.sigma;

import android.app.Activity;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;

public class ImageAdapter extends BaseAdapter {
private Context mContext;


public Integer[] Tattoos = {
        R.drawable.tattoo1, R.drawable.tattoo2,
        R.drawable.tattoo3, R.drawable.tattoo4,
        R.drawable.tattoo5, R.drawable.tattoo6,
        R.drawable.tattoo7, R.drawable.tattoo8,
        R.drawable.tattoo9, R.drawable.tattoo10, 
        R.drawable.tattoo11, R.drawable.tattoo12,
        R.drawable.tattoo13, R.drawable.tattoo14,
        R.drawable.tattoo15, R.drawable.tattoo16,
        R.drawable.tattoo17, R.drawable.tattoo18,
        R.drawable.tattoo19, R.drawable.tattoo20, 
        R.drawable.tattoo21, R.drawable.tattoo22,
        R.drawable.tattoo23, R.drawable.tattoo24,
        R.drawable.tattoo25, R.drawable.tattoo26,
        R.drawable.tattoo27, R.drawable.tattoo28,
        R.drawable.tattoo29, R.drawable.tattoo30, 
        R.drawable.tattoo31, R.drawable.tattoo32,
        R.drawable.tattoo33, R.drawable.tattoo34,
        R.drawable.tattoo35, R.drawable.tattoo36,
        R.drawable.tattoo37, R.drawable.tattoo38,
        R.drawable.tattoo39, R.drawable.tattoo40, 
        R.drawable.tattoo41, R.drawable.tattoo42,
        R.drawable.tattoo43, R.drawable.tattoo44,
        R.drawable.tattoo45, R.drawable.tattoo46,
        R.drawable.tattoo47, R.drawable.tattoo48,
        R.drawable.tattoo49, R.drawable.tattoo50, 
        R.drawable.tattoo51, R.drawable.tattoo52,
        R.drawable.tattoo53, R.drawable.tattoo54,
        R.drawable.tattoo55, R.drawable.tattoo56,
        R.drawable.tattoo57, R.drawable.tattoo58,
        R.drawable.tattoo59, R.drawable.tattoo60, 
        R.drawable.tattoo61, R.drawable.tattoo62,
        R.drawable.tattoo63, R.drawable.tattoo64,
        R.drawable.tattoo65, R.drawable.tattoo66,
        R.drawable.tattoo67, R.drawable.tattoo68,
        R.drawable.tattoo69, R.drawable.tattoo70, 
        R.drawable.tattoo71, R.drawable.tattoo72,
        R.drawable.tattoo73, R.drawable.tattoo74,
        R.drawable.tattoo75, R.drawable.tattoo76,
        R.drawable.tattoo77, R.drawable.tattoo78,
        R.drawable.tattoo79, R.drawable.tattoo80,
        R.drawable.tattoo81, R.drawable.tattoo82

};

// Constructor
public ImageAdapter(Context c){
    mContext = c;
}

public int getCount() {
    return Tattoos.length;
}

public Object getItem(int position) {
    return Tattoos[position];
}

public long getItemId(int position) {
    return 0;
}

public View getView(int position, View convertView, ViewGroup parent) {
    //This actually is a bad solution, because every time convertView is reused, you will still initialize new ImageView, which is wrong
    //ImageView imageView = new ImageView(this.mContext);
    //new BitmapWorkerTask(imageView).execute(Tattoos[position]);
    //return imageView;

    //Better solution
    ImageView imageView = null;

    if (convertView == null) {
        imageView = new ImageView(this.mContext);
        new BitmapWorkerTask(imageView).execute(Tattoos[position]);
        //create new ImageView if it is not present and populate it with some image
    } else {
        imageView = (ImageView) convertView;
        //re-use ImageView that already exists in memory
    }

return imageView;
}


class BitmapWorkerTask extends AsyncTask<Integer, Void, Bitmap> {
        private final WeakReference<ImageView> imageViewReference;
        private int data = 0;

        public BitmapWorkerTask(ImageView imageView) {
            // Use a WeakReference to ensure the ImageView can be garbage collected
            imageViewReference = new WeakReference<ImageView>(imageView);
        }

        // Decode image in background.
        @Override
        protected Bitmap doInBackground(Integer... params) {
            data = params[0];
            return decodeSampledBitmapFromResource(ImageAdapter.this.mContext.getResources(), data, 100, 100);
        }

        // Once complete, see if ImageView is still around and set bitmap.
        @Override
        protected void onPostExecute(Bitmap bitmap) {
            if (imageViewReference != null && bitmap != null) {
                final ImageView imageView = imageViewReference.get();
                if (imageView != null) {
                    imageView.setImageBitmap(bitmap);
                    imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
                    imageView.setLayoutParams(new GridView.LayoutParams(100, 70));
                }
            }
        }
    }

    public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
                                                         int reqWidth, int reqHeight) {

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeResource(res, resId, options);
    }

    public static int calculateInSampleSize(
            BitmapFactory.Options options, int reqWidth, int reqHeight) {
        // Raw height and width of image
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {

            // Calculate ratios of height and width to requested height and width
            final int heightRatio = Math.round((float) height / (float) reqHeight);
            final int widthRatio = Math.round((float) width / (float) reqWidth);

            // Choose the smallest ratio as inSampleSize value, this will guarantee
            // a final image with both dimensions larger than or equal to the
            // requested height and width.
            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
        }

        return inSampleSize;
    }

}

Which loads images asynchronously and does some additional magic on loaded resources.

This solution works fine for me and when you run your code, you can actually see images being loaded one at a time, starting with one that is of less weight and going upwards, i guess, because for every ImageView there will be a separate worker Thread, which will load and transform the resource and then apply it to the ImageView.

Proof:

标签
java
android
memory-leaks
android-gridview
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