Question

这段代码在我的真实设备上工作正常但如果我在模拟器上运行我的应用程序则会出现空指针异常 -

DiskLruImageCache.java

public DiskLruImageCache(Context context, String uniqueName,
            int diskCacheSize, CompressFormat compressFormat, int quality) {
        try {
            final File diskCacheDir = getDiskCacheDir(context, uniqueName);
            mDiskCache = DiskLruCache.open(diskCacheDir, APP_VERSION,
                    VALUE_COUNT, diskCacheSize);
            mCompressFormat = compressFormat;
            mCompressQuality = quality;
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

public void put(String key, Bitmap data) {

        DiskLruCache.Editor editor = null;
        try {
            editor = mDiskCache.edit(key);
            // showMsg("Editor = "+ editor);
            if (editor == null) {
                return;
            }

            if (writeBitmapToFile(data, editor)) {
                mDiskCache.flush();
                editor.commit();
                if (BuildConfig.DEBUG) {
                }
            } else {
                editor.abort();
                if (BuildConfig.DEBUG) {
                }
            }
        } catch (IOException e) {
            if (BuildConfig.DEBUG) {
            }
            try {
                if (editor != null) {
                    editor.abort();
                }
            } catch (IOException ignored) {
            }
        }

    }

public Bitmap getBitmap(String key) {

        Bitmap bitmap = null;
        DiskLruCache.Snapshot snapshot = null;
        try {

            snapshot = mDiskCache.get(key);
            if (snapshot == null) {
                return null;
            }
            final InputStream in = snapshot.getInputStream(0);
            if (in != null) {
                final BufferedInputStream buffIn = new BufferedInputStream(in);
                bitmap = BitmapFactory.decodeStream(buffIn).copy(
                        Config.ARGB_4444, true);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (snapshot != null) {
                snapshot.close();
            }
        }

        if (BuildConfig.DEBUG) {

        }

        return bitmap;

    }

我的LogCat：

07-09 08:29:45.877: E/AndroidRuntime(2266): FATAL EXCEPTION: main
07-09 08:29:45.877: E/AndroidRuntime(2266): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.apper.main/com.apper.main.MyFragmentActivity}: java.lang.NullPointerException
07-09 08:29:45.877: E/AndroidRuntime(2266):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at android.os.Looper.loop(Looper.java:137)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at android.app.ActivityThread.main(ActivityThread.java:5041)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at java.lang.reflect.Method.invokeNative(Native Method)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at java.lang.reflect.Method.invoke(Method.java:511)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
07-09 08:29:45.877: E/AndroidRuntime(2266):     at dalvik.system.NativeStart.main(Native Method)
07-09 08:29:45.877: E/AndroidRuntime(2266): Caused by: java.lang.NullPointerException
07-09 08:29:45.877: E/AndroidRuntime(2266):     at com.apper.util.DiskLruImageCache.getBitmap(DiskLruImageCache.java:109)

我尝试在我的Android清单上设置外部存储但没有运气 -

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Answer 1

如果Emulator没有指定缓存文件，则模拟器的默认行为是使用临时文件。

有关磁盘映像的更多信息，请使用-help-disk-images。见http://developer.android.com/tools/help/emulator.html

DiskLruCache模拟器上的空指针异常

1 个答案: