Jdk1.4 和jdk1.5中的StringBuffer的不同

        if (offset > value. length - count) {

            throw new StringIndexOutOfBoundsException(offset + count);

        }

        char [] v = new char [count];

        System.arraycopy(value, offset, v, 0, count);

        this . offset = 0;

        this . count = count;

        this . value = v;

}

重新分配了内存空间

再来看看