JAVA1

public static void main(String[] args) throws IOException {
        System.out.println(System.getProperty("user.dir"));//这里输出 D:\workspace
       
        System.setProperty("user.dir","D:/temp");
        System.out.println(System.getProperty("user.dir"));//这里输出 D:\temp
        File file = new File("HELLO.txt");
        System.out.println(file.getAbsolutePath());    //这里输出 D:\temp\HELLO.txt
        System.out.println(file.createNewFile());    //这里输出 true
        System.out.println(file.getAbsolutePath());    //这里输出 D:\temp\HELLO.txt
}