安卓 'java.io.File android.content.Context.getCacheDir()' on a null object re

我已经动态的获取  读写的权限了，还是报错 
下面是错误日志：哪位大神帮忙解决一下：
BOARD=NXT-AL10
CPU_ABI2=
HOST=wuhjk0387cna
versionName=1.0
IS_TREBLE_ENABLED=true
SUPPORTED_64_BIT_ABIS=[Ljava.lang.String;@2d3204b
CPU_ABI=arm64-v8a
PERMISSIONS_REVIEW_REQUIRED=false
IS_USERDEBUG=false
SDK_INT=26
DISPLAY=NXT-AL10 8.0.0.839(C00)
SUPPORTED_ABIS=[Ljava.lang.String;@cbdca28
FINGERPRINT=HUAWEI/NXT-AL10/HWNXT:8.0.0/HUAWEINXT-AL10/839(C00):user/release-keys
PRODUCT=NXT-AL10
HIDE_PRODUCT_INFO=false
ID=HUAWEINXT-AL10
replacements=[Ljava.lang.String;@f317627
HWFINGERPRINT=//
TYPE=user
SERIAL=5LM0217221000625
NO_HOTA=false
IS_CONTAINER=false
IS_ENG=false
DEVICE=HWNXT
TIME=1543343599000
MODEL=HUAWEI NXT-AL10
IS_USER=true
MANUFACTURER=HUAWEI
USER=test
versionCode=1
BRAND=HUAWEI
SUPPORTED_32_BIT_ABIS=[Ljava.lang.String;@89b3d1a
matchers=[Ljava.lang.String;@6a010e6
HARDWARE=hi3650
IS_DEBUGGABLE=false
BOOTLOADER=unknown
RADIO=unknown
TAG=Build
UNKNOWN=unknown
IS_EMULATOR=false
TAGS=release-keys
java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File android.content.Context.getCacheDir()' on a null object reference
at com.xyxl.yitiji.add.DataCleanManager.cleanInternalCache(DataCleanManager.java:10)
at com.xyxl.yitiji.main.MainActivity.onBackPressed(MainActivity.java:438)
at android.app.Activity.onKeyUp(Activity.java:3161)
at android.view.KeyEvent.dispatch(KeyEvent.java:2779)
at android.app.Activity.dispatchKeyEvent(Activity.java:3492)
at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:415)
at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:5191)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:5063)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4581)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4634)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4600)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4727)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4608)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4784)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4581)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4634)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4600)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4608)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4581)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4634)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4600)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4760)
at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:4921)
at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:2599)
at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:2160)
at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:2151)
at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:2574)
at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141)
at android.os.MessageQueue.nativePollOnce(Native Method)
at android.os.MessageQueue.next(MessageQueue.java:379)
at android.os.Looper.loop(Looper.java:144)
at android.app.ActivityThread.main(ActivityThread.java:7529)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)