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                   byte b1 = 10;
                   byte b2 = 20;
                   byte b3 = b1 + b2; //Óï·¨´íÎó£¬ÀàÐͲ»Æ¥Åä
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                   int n = -1;
                   boolean b1 = (n >= 0) && (n < 10);
                   boolean b2 = (n >= 0) & (n < 10);
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