ECLIPSE 编制的APP有时候启动不成功，有时候启动又能成功.

[motingwei]

这是报的错误，不知道是什么原因，请高手指点。
01-30 16:27:07.273: E/AndroidRuntime(7205): FATAL EXCEPTION: Thread-6229
01-30 16:27:07.273: E/AndroidRuntime(7205): Process: com.example.mdbs, PID: 7205
01-30 16:27:07.273: E/AndroidRuntime(7205): java.lang.NullPointerException: Attempt to invoke virtual method 'int java.io.InputStream.read(byte[], int, int)' on a null object reference
01-30 16:27:07.273: E/AndroidRuntime(7205): at com.example.mdbs.MainActivity.ModbusRecev(MainActivity.java:937)
01-30 16:27:07.273: E/AndroidRuntime(7205): at com.example.mdbs.MainActivity$13.run(MainActivity.java:642)

[SemiraChen]

java.lang.NullPointerException: Attempt to invoke virtual method 'int java.io.InputStream.read(byte[], int, int)' on a null object reference 空指针错误 用read的地方为空了呗