OCJP(310-065)多項(xiàng)選擇題每日一練(2019.10.14)

來源：考試資料網(wǎng)

1 Given：

Which three changes should be made to adapt this class to be used safely by multiple threads？（）

2 Which two statements are true about the hashCode method？（）

3 Which two code fragments will execute the method doStuff（） in a separate thread？（）

4 Which two scenarios are NOT safe to replace a StringBuffer object with a StringBuilder object？（）

5 Given：

Which two， independently， will allow Sub to compile？（）