boolean java.io.File.createNewFile() throws IOException
public boolean createNewFile ()
Since: API Level 1
Creates a new, empty file on the file system according to the path information stored in this file. This method returns true if it creates a file, false if the file already existed. Note that it returns false even if the file is not a file (because it's
a directory, say).
在文件系统中根据保存在文件中的路径信息，创建一个新的空文件。如果创建成功就会返回true，如果文件存在返回false。注意：如果他已经存在但不是文件，可能是目录也会返回false。
This method is not generally useful. For creating temporary files, use createTempFile(String, String) instead. For reading/writing files, use FileInputStream, FileOutputStream, or RandomAccessFile, all of which can create files.
这个方法不是很常用。创建临时文件通常使用createTempFile(String,String)替代。创建读/写文件使用FileInputStream，FileOutputStream，或者RandmomAccessFile,他们都可以创建文件。
Note that this method does not throw IOException if the file already exists, even if it's not a regular file. Callers should always check the return value, and may additionally want to call isFile().
注意，这个方法如果遇到文件存在不会抛出异常，及时是一个不规则的文件。调用者应该总是检查返回值，或者需要额外的调用isFile()来判断。
Returns
true if the file has been created, false if it already exists.
Throws
IOException if it's not possible to create the file.
如果不能创建文件就会抛出异常。
例如：
File file = new File(SDPATH + fileName);
file.createNewFile();