System.out.println的源代码解释
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悬赏园豆：5
[已解决问题]
解决于 2013-03-16 23:20
查看System类可知，out是这样定义的fianl static PrintStream out = null;
为什么使用System.out.println是不会报java.lang.NullPointerException（空指针异常）
最佳答案
0
可以看一下nullPrintStream（）函数注释：
/**
* The following two methods exist because in, out, and err must be
* initialized to null. The compiler, however, cannot be permitted to
* inline access to them, since they are later set to more sensible values
* by initializeSystemClass().
*/
在initializeSystemClass（）函数中对out做了初始化。
setOut0(new PrintStream(new BufferedOutputStream(fdOut, 128), true));
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Thanks
