我在我的应用程序中使用ThreadHandler，
public class MessageThread extends HandlerThread {
Handler mHandler;
public MessageThread() {
super("Message Thread");
}
public void queueProcessMessage(msgObject mObj) {
mHandler.obtainMessage(PROCESS_MESSAGE, mObj).sendToTarget();
}
@Override
protected void onLooperPrepared() {
Commons.logIt("OnLoopPrep");
mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case PROCESS_MESSAGE:
process_message((msgObject) msg.obj);
break;
default:
break;
}
}
};
}
process_message(msgObject obj) {
//Do stuff
}
}
我在onCreate（）中初始化它，就像这样，
public void onCreate(Bundle savedInstanceState) {
MessageThread mThread = new MessageThread();
mThread.start();
mThread.getLooper();
if (mThread != null)
mThread.queueProcessMessage(Object);// this is the line the compiler is pointing at.
}
它工作正常，问题是我需要添加其他东西，我必须开始另一个活动等待结果所以我必须初始化/使用它，如下所示onActivityResult在onCreate之前被调用，当我开始结果的活动，这次我收到错误
java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Message android.os.Handler.obtainMessage(int, java.lang.Object)' on a null object reference
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == IMAGE_ACTIVITY_REQUEST_CODE) {
if (resultCode == Activity.RESULT_OK) {
MessageThread mThread = new MessageThread();
mThread.start();
mThread.getLooper();
mThread.queueProcessMessage(new msgObject("stuff"));
}
}
}
看起来线程没有初始化，我在这里缺少什么？
编辑1，
在讨论了这个问题之后，看起来处理器初始化需要花费一些时间，我这样做了，它很难看但是它有效，我应该怎么做？
public void queueProcessMessage(msgObject mObj) {
while (mHandler == null)
Log.i(TAG, "Not init yet"); //It keeps on looping here
mHandler.obtainMessage(PROCESS_MESSAGE, mObj).sendToTarget();
}