why new FileWriter("abc.txt") creates a new file and new File("abc.txt") does not?

Question

new File("abc.txt") does not create actual file while new FileWriter("abc.txt") creates a file on disk. While going through source code i found that new FileWriter("abc.txt") eventually creates an object of file like new File()

Answer 1

Constructor of Class java.io.File does not create file on disk. It is just a abstraction over the file path. The file is created when you write to the file.

When you are creating FileWriter it calls constructor of FileOutputStream that calls a sequence of security checks and then invokes:

if (append) {
    openAppend(name);
} else {
    open(name);
}

Invocation of open() creates file on disk.

EDIT:

Here is how open() is defined:

/**
 * Opens a file, with the specified name, for writing.
 * @param name name of file to be opened
 */
private native void open(String name) throws FileNotFoundException;

Answer 2

I think file.createNewFile() creates the new file in actual.. please see following code for detal...

  File file = new File("D:\\tables\\test.sql");

            // if file does not exists, then create it
            if (!file.exists()) {
                file.createNewFile();
            }

            FileWriter fw = new FileWriter(file.getAbsoluteFile());