关闭串口时闪退，closeSerialPort方法里面close这行报错

[MarcoJF888]

也是关闭串口的时候报错

  if (null != mFd) {
        close();
        mFd = null;
    }

这个close这里

567 2658-2691/? E/art: JNI DETECTED ERROR IN APPLICATION: fid == null
2020-05-22 11:39:11.567 2658-2691/? E/art: in call to GetObjectField
2020-05-22 11:39:11.567 2658-2691/? E/art: from void com.kongqw.serialportlibrary.SerialPort.close()
2020-05-22 11:39:11.567 2658-2691/? E/art: "Timer-2" prio=5 tid=18 Runnable
2020-05-22 11:39:11.567 2658-2691/? E/art: | group="main" sCount=0 dsCount=0 obj=0x12f2fca0 self=0xb16ac600
2020-05-22 11:39:11.567 2658-2691/? E/art: | sysTid=2691 nice=0 cgrp=default sched=0/0 handle=0xb2ba6920
2020-05-22 11:39:11.567 2658-2691/? E/art: | state=R schedstat=( 1653461 1101693 8 ) utm=0 stm=0 core=3 HZ=100
2020-05-22 11:39:11.567 2658-2691/? E/art: | stack=0xb2aa4000-0xb2aa6000 stackSize=1038KB
2020-05-22 11:39:11.567 2658-2691/? E/art: | held mutexes= "mutator lock"(shared held)
2020-05-22 11:39:11.567 2658-2691/? E/art: native: #00 pc 0034f0ad /system/lib/libart.so (_ZN3art15DumpNativeStackERNSt3__113basic_ostreamIcNS0_11char_traitsIcEEEEiP12BacktraceMapPKcPNS_9ArtMethodEPv+128)
2020-05-22 11:39:11.567 2658-2691/? E/art: native: #1 pc 0032f96d /system/lib/libart.so (_ZNK3art6Thread9DumpStackERNSt3__113basic_ostreamIcNS1_11char_traitsIcEEEEbP12BacktraceMap+632)
2020-05-22 11:39:11.567 2658-2691/? E/art: native: #2 pc 00238381 /system/lib/libart.so (ZN3art9JavaVMExt8JniAbortEPKcS2+1188)
2020-05-22 11:39:11.567 2658-2691/? E/art: native: #3 pc 002393db /system/lib/libart.so (ZN3art9JavaVMExt9JniAbortFEPKcS2_z+66)
2020-05-22 11:39:11.567 2658-2691/? E/art: native: #4 pc 0026fad3 /system/lib/libart.so (ZN3art3JNI14GetObjectFieldEP7_JNIEnvP8_jobjectP9_jfieldID+514)
2020-05-22 11:39:11.567 2658-2691/? E/art: native: #5 pc 00000b67 /system/priv-app/rktools/rktools.apk (???)
2020-05-22 11:39:11.567 2658-2691/? E/art: native: #6 pc 0003996f /data/dalvik-cache/arm/system@priv-app@rktools@rktools.apk@classes.dex (Java_com_kongqw_serialportlibrary_SerialPort_close+74)
2020-05-22 11:39:11.567 2658-2691/? E/art: at com.kongqw.serialportlibrary.SerialPort.close(Native method)
2020-05-22 11:39:11.567 2658-2691/? E/art: at com.intelligym.rk3288tools.device.b.a.a(SerialPortManager.java:107)
2020-05-22 11:39:11.567 2658-2691/? E/art: at