java – 为什么Thread类中的setName分配给一个字符数组？为什么

private char name[]; // why not "private String name;"

public final void setName(String name) {
    checkAccess();
    this.name = name.toCharArray();
    }

此名称是从本机代码访问的,因此与使用Java类型的mangle相比,它更容易处理char数组. core-lib-devs邮件列表不久前讨论过这个问题,这是一个来自该主题的 link到一封邮件.最初的问题表明“相当多的时间进入Thread.setName调用,我认为其中很大一部分是进行新的char分配和复制char数组等”.引用答案：

There was an RFE for this way back in late 2002:

4745629 (thread) Thread.setName does needless string allocations
(don’t use char[])

The initial eval in 2002 stated:

“I can’t imagine that this seriously impacts the performance of any
real program. Furthermore,changing the fields in Thread is
problematic due to the close relationship of this class with the VM.
That said,it might be worth addressing this in the context of some
Thread code-cleanup.”

Then in 2005 it was closed as “will not fix”:

“There are dependencies on the name representation being a char array in the JVM and this RFE must be respectfully rejected.”