Question

找不到我得到的原因＆＃34;空指针异常＆＃34; 。我可以给出一个明确的检查，看看＆＃34; getStorageState是否为空＆＃34;但这并不能解释为什么我会收到此错误。错误是：

java.lang.NullPointerException
at android.os.Environment.getStorageState(Environment.java:719)
at android.os.Environment.getExternalStorageState(Environment.java:694)
at com.ciqual.android.insight.sessionService.RemoveFiles(SessionService.java:664)
com.vyshas.android.sessionService.onEndSession(SessionService.java:460)

at :(错误指向的行是这个:)（见于豆豆4.3和kitkat）

if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            //
        }

Answer 1

Environment.MEDIA_MOUNTED.equals（Environment.getExternalStorageState）不会导致NPE，而Environment.getExternalStorageState（）。equals（Environment.MEDIA_MOUNTED）确实会导致NPE并导致应用程序崩溃。

我仍然不知道为什么getExternalStorageState为null虽然我已经设置了权限，但atleast解决方案不会使应用程序崩溃。

Answer 2

我从Android 4.3获得了类似的报告。

源代码是：

    /**
     * Gets the current state of the primary "external" storage device.
     *
     * @see #getExternalStorageDirectory()
     */
    public static String getExternalStorageState() {
        try {
            IMountService mountService = IMountService.Stub.asInterface(ServiceManager
                    .getService("mount"));
            final StorageVolume primary = getPrimaryVolume();
            return mountService.getVolumeState(primary.getPath());
        } catch (RemoteException rex) {
            Log.w(TAG, "Failed to read external storage state; assuming REMOVED: " + rex);
            return Environment.MEDIA_REMOVED;
        }
    }

我无所事事，只能抓住它。

Environment.getExternalStorageState（）上的NPE？

2 个答案: