boat[1] = new Powerboat(33, 2009, 2, 2);
index写错了,boat[2]为null
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签名档: http://feiyun0112.cnblogs.com/
index写错了,boat[2]为null
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签名档: http://feiyun0112.cnblogs.com/
boat[0] = new Boat(11, 2008);
boat[1] = new Sailboat(22, 2009, 2, 1);
boat[1] = new Powerboat(33, 2009, 2, 2);
boat[1] = new Sailboat(22, 2009, 2, 1);
boat[2] = new Powerboat(33, 2009, 2, 2);