Conversion of numeric string to integer in android

Question

In the following code, when i try to convert msgStr to integer the app force closes. Could anyone tell me the reason? Is it because msgStr is not in proper format? Note: msg is an obj got through handler. msgStr is a numeric string.

MainActivity code:

private handleMessage(Message msg){
byte[] byteArr = (byte[])msg.obj;
String msgStr = new String(byteArr,"utf-8");
try{
int val = Integer.parseInt(msgStr);
}catch(Exception e){
e.printStackTrace;
}

Bluetooth connection thread:

  private class ConnectedThread extends Thread {
  private final BluetoothSocket mmSocket;
  private final InputStream mmInStream;
  private final OutputStream mmOutStream;

 public ConnectedThread(BluetoothSocket socket) {
     mmSocket = socket;
    InputStream tmpIn = null;
    OutputStream tmpOut = null;

    // Get the input and output streams, using temp objects because
    // member streams are final
    try {
        tmpIn = socket.getInputStream();
        tmpOut = socket.getOutputStream();
    } catch (IOException e) { }

    mmInStream = tmpIn;
    mmOutStream = tmpOut;
  }

  public void run() {
    byte[] buffer = new byte[1024];  // buffer store for the stream
    int bytes; // bytes returned from read()

    // Keep listening to the InputStream until an exception occurs
    while (true) {
        try {
            // Read from the InputStream
            bytes = mmInStream.read(buffer);
            // Send the obtained bytes to the UI activity
            mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
                    .sendToTarget();
        } catch (IOException e) {
            break;
        }
    }
  }

Now can anyone tell what can be the problem? Also if the mmInStream consists of numeric data, then how to differentiate and store 2-digit data from 3 digit data in the byte array buffer?

Answer 1

尝试

String msgString = new String(...);

Answer 2

Change this

String msgStr = String(byteArr);

to

String msgStr = new String(byteArr);

This post may help you How To Convert Byte[] Array To String In Java

Answer 3

String s = new String(byteArr);
System.out.println("Output : " + s);

Answer 4

It's because you're casting the byte array to a string and that won't work. You need to use this constructor :

String msgStr = new String(byteArr, "UTF-8");

Of course, the UTF-8 varies based on the character set you're using.

Answer 5

First of all convert Byte to String by following code.

String msg = new String(bytes, "UTF-8");

Then convert your string into integer as follow.

int m = Integer.parseInt(msg);

Answer 6

try to directly convert the message to String:

String msgStr = (String)msg.obj;

and if this not working also try to not convert it to Integer , may be the String retrieved isn't an integer.

---

Also you can send the Handler message directly as integer without having to convert it:

yourhandlername.obtainMessage(what, arg1, arg2, obj).sendToTarget();

arg1 : is an Integer

arg2 : is an Integer

So, when receiving:

int val = msg.arg1;