Android ImageSwitcher OutOfMemoryError

Question

我正在尝试创建一个ImageSwitcher来浏览DCIM上的相机图像。当我浏览图片时，我得到了一个OutOfMemory错误。这是非常有意义的，如果内存是分配给每一个相当大的图像观看。我研究过其他类似的问题，但当我切换到新的图像时，我想不出如何释放旧图像的记忆。

public class MainActivity extends ActionBarActivity {

    private ImageView     imageView;
    private ImageSwitcher imageSwitcher;
    private String        imageDir;
    private File          imageFile;
    private String[]      imageNames;
    private int           i;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);        

        imageSwitcher = (ImageSwitcher)findViewById(R.id.imageSwitcher1);
        imageDir      = getString(R.string.image_dir);
        imageFile     = new File(imageDir);
        imageNames    = imageFile.list();
        i             = imageNames.length - 1;

        imageSwitcher.setFactory(new ViewFactory() {
            @TargetApi(Build.VERSION_CODES.HONEYCOMB)
            @Override
            public View makeView() {
                // I tried testing for null here but that doesn't work
                imageView = new ImageView(getApplicationContext());
                imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
                imageView.setLayoutParams(new 
                        ImageSwitcher.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
                return imageView;
            }
        });
    }

    public void previous(View view) {
        Animation in  = AnimationUtils.loadAnimation(this, android.R.anim.slide_out_right);
        Animation out = AnimationUtils.loadAnimation(this, android.R.anim.slide_in_left);
        imageSwitcher.setInAnimation(out);
        imageSwitcher.setOutAnimation(in);
        Uri imageUri = Uri.parse(imageDir+"/"+imageNames[i]);
        imageSwitcher.setImageURI(imageUri);
        decrementImage();
    }

    public void decrementImage() {
        if (i == 0) {
            i = imageNames.length - 1;
        } else {
            i--;
        }
    }
}

Answer 1

解决办法：

public void previous(View view) {
    Animation in  = AnimationUtils.loadAnimation(this, android.R.anim.slide_out_right);
    Animation out = AnimationUtils.loadAnimation(this, android.R.anim.slide_in_left);
    imageSwitcher.setInAnimation(out);
    imageSwitcher.setOutAnimation(in);
    Uri imageUri = Uri.parse(imageDir+"/"+imageNames[i]);
    imageSwitcher.setImageURI(null); // THIS FIXED THE OOM ERROR
    imageSwitcher.setImageURI(imageUri);
    decrementImage();
}