ObjectInputStream readObject in while Loop

问题:

Is it possible to read from ObjectInputStream in while loop which will terminate by exception thrown by socket timeout socket.setSoTimeout(4000);

while(Object obj = ois.readObject()) {  <-- Not Working
//do something with object    
}

回答1:

while(Object obj = ois.readObject()) {  <-- Not Working
//do something with object    
}

When you say 'not working', what you really mean is 'not compiling', for reasons that are stated in the compiler message: Object isn't a boolean expression, and you can't declare a variable in a while condition.

However the code isn't valid anyway. The correct way to read to end of stream of an arbitrary ObjectInputStream is catch EOFException, for example as follows:

try
{
    for (;;)
    {
        Object object = in.readObject();
        // ...
    }
}
catch (SocketTimeoutException exc)
{
    // you got the timeout
}
catch (EOFException exc)
{
    // end of stream
}
catch (IOException exc)
{
    // some other I/O error: print it, log it, etc.
    exc.printStackTrace(); // for example
}

Note that the suggestion in comments to test the readObject() return value for null is not correct. It will only return null if you wrote a null.