java 可以用file.rename 来替换现有文件吗？
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can file.renameTo replace a existing file?
提问by akshay
// File (or directory) to be moved
File file = new File("filename");
// Destination directory
File dir = new File("directoryname");
// Move file to new directory
boolean success = file.renameTo(new File(dir, file.getName()));
if (!success) {
// File was not successfully moved
//can it be because file with file name already exists in destination?
}
If the file with name 'filename' already exists in the destination will it be replaced with a new one?
如果目标文件中已经存在名为“filename”的文件，它会被一个新文件替换吗？
采纳答案by mnicky
According to Javadoc:
根据Javadoc：
Many aspects of the behavior of this method are inherently platform-dependent: The rename operation might not be able to move a file from one filesystem to another, it might not be atomic, and it might not succeed if a file with the destination abstract pathname already exists. The return value should always be checked to make sure that the rename operation was successful.
此方法行为的许多方面本质上是平台相关的：重命名操作可能无法将文件从一个文件系统移动到另一个文件系统，它可能不是原子的，并且如果具有目标抽象路径名的文件可能不会成功已经存在。应始终检查返回值以确保重命名操作成功。
回答by stacker
From Javadoc:
来自 Javadoc：
The rename operation might not be able to move a file from one filesystem to another, it might not be atomic, and it might not succeed if a file with the destination abstract pathname already exists.
重命名操作可能无法将文件从一个文件系统移动到另一个文件系统，它可能不是原子的，并且如果具有目标抽象路径名的文件已经存在，它可能不会成功。
I tested the following code:
我测试了以下代码：
It works the first time, second time it fails as expected. To move a file you should delete or rename the destination if required.
它第一次工作，第二次它按预期失败。要移动文件，您应该根据需要删除或重命名目标。
public class Test {
public static void main(String[] args) throws IOException {
File file = new File( "c:\filename" );
file.createNewFile();
File dir = new File( "c:\temp" );
boolean success = file.renameTo( new File( dir, file.getName() ) );
if ( !success ) {
System.err.println( "succ:" + success );
}
}
}
回答by Rostislav Matl
As it is system dependent you should not expectit to behave this or other way. Check it and implement your own logic.
由于它依赖于系统，因此您不应期望它以这种或其他方式行事。检查它并实现你自己的逻辑。
