sendMessage and sendEmptyMessage

/*** Sends a Message containing only the what value.*/public final boolean sendEmptyMessage(int what){　　return sendEmptyMessageDelayed(what, 0);}

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/*** Pushes a message onto the end of the message queue after all pending messages* before the current time. It will be received in {@link #handleMessage},* in the thread attached to this handler.*/public final boolean sendMessage(Message msg){　　return sendMessageDelayed(msg, 0);}

sendEmptyMessage()只能放int型数据，而sendMessage可以放其他的数据。