这个tmp变量在android样例蓝牙聊天应用程序中的用途是什么

Question

private class ConnectThread extends Thread {
    private final BluetoothSocket mmSocket;
    (...)
    public ConnectThread(BluetoothDevice device, boolean secure) {
        (...)
        BluetoothSocket tmp = null;
        (...)
        try {
            if (secure) {
                tmp = device.createRfcommSocketToServiceRecord(MY_UUID_SECURE);
            } else {
                tmp = device.createInsecureRfcommSocketToServiceRecord(MY_UUID_INSECURE);
            }
        } catch (IOException e) {
            Log.e(TAG, "Socket Type: " + mSocketType + "create() failed", e);
        }
        mmSocket = tmp;
    }
    (...)

private class ConnectThread extends Thread {
    private final BluetoothSocket mmSocket;
    (...)
    public ConnectThread(BluetoothDevice device, boolean secure) {
        (...)
        try {
            if (secure) {
                mmSocket =  device.createRfcommSocketToServiceRecord(MY_UUID_SECURE);
            } else {
                mmSocket =  device.createInsecureRfcommSocketToServiceRecord(MY_UUID_INSECURE);
            }
        } catch (IOException e) {
            Log.e(TAG, "Socket Type: " + mSocketType + "create() failed", e);
        }
    }

Answer 1

简而言之，因为mmsocket被标记为final变量。

让我们看看你的代码版本。如果方法createrfcommsockettoServiceRecord或方法createInsecurerfcommsockettoServiceRecord引发异常，则变量未初始化。因此，临时变量确保至少有null要分配给MMSocket。

就是这个原因。