Android 操作和使用从Arduino USB获取的字符串
我可以得到字符串来自USB串行工作时,它是在原始格式。但一旦我尝试使用Double.valueOf或其他方法将其转换为数字,应用程序就会崩溃Android 操作和使用从Arduino USB获取的字符串,android,logging,usb,Android,Logging,Usb,我可以得到字符串来自USB串行工作时,它是在原始格式。但一旦我尝试使用Double.valueOf或其他方法将其转换为数字,应用程序就会崩溃 public void onReceivedData(byte[] arg0) { String data = null; try { data = new String(arg0, "UTF-8"); Double waterLevel=Double.valueOf(data); tvAp
public void onReceivedData(byte[] arg0) {
String data = null;
try {
data = new String(arg0, "UTF-8");
Double waterLevel=Double.valueOf(data);
tvAppend(textView, waterLevel+"m");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
当使用此选项时,上述操作有效,并且仅尝试将字符串转换为双精度或浮点值会导致问题:
String waterLevel=data+"m";
错误消息:
2019-02-05 19:02:06.746 915-5126/? E/AwareLog: CPUFeatureAMSCommunicator: set app boost but type is unknown
2019-02-05 19:02:06.824 421-450/? E/DynamicFpsPolicy: FpsInfo: 1a500000000 can not find FpsPolicyService
2019-02-05 19:02:07.683 915-1498/? E/TouchFilter: setTouchFilter LOG Enable prameter: 0
2019-02-05 19:02:08.237 421-450/? E/DynamicFpsPolicy: FpsInfo: 1a500000000 can not find FpsPolicyService
2019-02-05 19:02:08.454 12270-12270/com.jorc.loggergeneral.jorclogger E/SpannableStringBuilder: SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
2019-02-05 19:02:08.455 12270-12270/com.jorc.loggergeneral.jorclogger E/SpannableStringBuilder: SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
2019-02-05 19:02:09.432 12270-12467/? E/AndroidRuntime: FATAL EXCEPTION: Thread-6
Process: com.jorc.loggergeneral.jorclogger, PID: 12270
java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1842)
at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
at java.lang.Double.parseDouble(Double.java:539)
at java.lang.Double.valueOf(Double.java:503)
at com.jorc.loggergeneral.jorclogger.MainActivity$1.onReceivedData(MainActivity.java:55)
at com.felhr.usbserial.UsbSerialDevice$WorkerThread.onReceivedData(UsbSerialDevice.java:209)
at com.felhr.usbserial.UsbSerialDevice$WorkerThread.run(UsbSerialDevice.java:184)
2019-02-05 19:02:09.483 915-1082/? E/InputDispatcher: channel '4af7ed1 com.jorc.loggergeneral.jorclogger/com.jorc.loggergeneral.jorclogger.MainActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
2019-02-05 19:02:09.535 421-450/? E/DynamicFpsPolicy: FpsInfo: 1a500000000 can not find FpsPolicyService
2019-02-05 19:02:09.706 915-1284/? E/TouchFilter: setTouchFilter LOG Enable prameter: 0
2019-02-05 19:02:09.938 1135-1135/? E/FullInputEventModel: onStartInput event aborted: ejh: could not obtain extracted text (class ejh)
2019-02-05 19:02:10.976 485-485/? E/Thermal-daemon: [battery] temp_new :32 temp_old :31
2019-02-05 19:02:10.979 485-485/? E/Thermal-daemon: Report temperature: [battery] temp :32 report_threshold:1
2019-02-05 19:02:11.731 915-1284/? E/TouchFilter: setTouchFilter LOG Enable prameter: 0
你的答案在stacktrace里。您尝试解析一个空字符串。
找个时间尝试使用调试器…您的答案在stacktrace中。您尝试解析一个空字符串。
找个时间尝试使用调试器…我可以用catch短语处理这个问题。你不能在第一行使用if短语来避免它:
if(data.length()!=0 && data.length()>0){
try {
tvAppend(textView, Double.parseDouble(data)*6 + "m\n");
} catch(Exception e) {
// or some value to mark this field is wrong. or make a function
}
}
我可以用流行语来处理这个问题。你不能在第一行使用if短语来避免它:
if(data.length()!=0 && data.length()>0){
try {
tvAppend(textView, Double.parseDouble(data)*6 + "m\n");
} catch(Exception e) {
// or some value to mark this field is wrong. or make a function
}
}
它不是一个空字符串。我可以在简单地添加到文本视图时看到值。我尝试添加它,然后对几个值起作用,然后做同样的事情。如果(!data.isEmpty()){test=Double.valueOf(data);}它不是空字符串。我可以在简单地添加到文本视图时看到值。我尝试添加它,然后对几个值起作用,然后做同样的事情。如果(!data.isEmpty()){test=Double.valueOf(data);}