转Java一段时间了,发现Java里的有些习惯跟Win32下编程有点差别,初学者很容易上当
1.字符串比较
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为什么呢?因为实际上Java里除简单类型外,==比较的实际是实例的地址
String比较内容是否相同应该用 a.equals(b) / a.equalsIgnoreCase(b)
不过同时我也发现一个很有意思的问题
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我想这应该是Java为了节省资源,给a/b分配的是同一个地址吧
未验证,高手指教
顺变说一下,Java里String内容是不可更改的
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因此如果一个String内容会被频繁修改,应该用StringBuffer替代
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2. 数组做参数
数组做为参数时,在函数内可以修改其内容,但不可以改变其地址
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3. 数组索引越界
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4. ResultSet读取
如果某一列值为NULL,当用getString取此列值时返回的不是空字符串,而是字符串"NULL" (JDK1.5已修正)