Java开发网 - [讨论]两个基础问题

Topic: [讨论]两个基础问题

1.[讨论]两个基础问题

Posted by: href
Posted on: 2004-09-03 10:18

不知道大家写代码的时候会不会注意
1。在比较null时，到底应该
x == null
or null == x
呢？两者据说是有区别的。

2。在int转String时，又用哪种方式最高效又简洁呢？
2.1 String s = i + "";
2.2 String s = Integer.toString(i);
2.3 String s = String.valueOf(i);
后两者好像是等价的

没事闲着讨论讨论

2.Re:[讨论]两个基础问题 [Re: href]	Copy to clipboard
Posted by: why Posted on: 2004-09-03 10:41 I read that String.valueOf(int) calls Integer.toString(int), and s = i + "" further involves creation of StringBuffer If you're serious about this, you may either 1. do some benchmarking stuff 2. take a look at Sun's Java source 3. compare compiled Java Assembly Language of them

3.Re:[讨论]两个基础问题 [Re: href]	Copy to clipboard
Posted by: href Posted on: 2004-09-03 11:05 从source看不出 2.1和2.2,2.3的区别来。老大，第三点用肉眼难度太大了吧

4.Re:[讨论]两个基础问题 [Re: href]

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Posted by: why
Posted on: 2004-09-03 11:16

href wrote:
从source看不出 2.1和2.2,2.3的区别来。
老大，第三点用肉眼难度太大了吧

应该看得出 2.2 和 2.3 之间的分别
第三点，看不见笑脸吗？再来一个 Wink

from String.java in src.zip of J2SDK
public static String valueOf(Object obj) {
return (obj == null) ? "null" : obj.toString();
}

from Integer.java
public String toString() {
return String.valueOf(value);
}
What are you talking about?