Create a folder in the project :

File directory_1 = new File("new");	// khai bao 1 folder ten la new trong project
directory_1.mkdir();		// lenh tao folder new tren o dia

With our first order only declared but not yet created, to create 1 folder must write the second order.

Create a folder in the path of any:

File directory_2 = new File(directory_1, "new1");	// tao thu muc new1 trong thu muc new vua tao
directory_2.mkdir();

Create a file in the project:

File file = new File("test.txt");	// nam trong project
try {
	file.createNewFile();		// tao file test.txt
} catch (IOException e) {
	e.printStackTrace();
}

When creating the file may be some exceptions, we have to place order file.createNewFile(); trong try catch.
Create a file in the directory any similar Folder, we just need to add the path of the report file.

Intelligent Code flowers:

import java.io.File;
import java.io.IOException;

public class FileAndDirectory {
	public static void main(String[] args) {
		
		File directory_1 = new File("new");	// khai bao 1 folder ten la new trong project
		directory_1.mkdir();		// lenh tao folder new tren o dia
		
		
		File directory_2 = new File(directory_1, "new1");	// tao thu muc new1 trong thu muc new vua tao
		directory_2.mkdir();		
		
		//khai bao 3 file nam trong cac thu muc khac nhau 
		File file_1 = new File("test.txt");	// nam trong project
		File file_2 = new File(directory_1,"test1.txt");	// nam trong directory_2 (new1)
		File file_3 = new File("/media/quan/DATA/Dropbox/STUDY/PROGRAM/Java/code/JavaBasic/new/new1","test2.txt");
		// new la directory1, new1 la directory2
		try {
			file_1.createNewFile();		// tao file test.txt
			file_2.createNewFile();		// tao file test1.txt
			file_3.createNewFile();		// tao file test2.txt
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

Do yourself lotion should be used ubuntu /media/quan/DATA/…. If you use windows paths can be C:foldertext.txt
To get the path of the folder you can see all the instructions below:
Get the file path in Java - Get File Path in Java
Directories in Ubuntu - The path folder in Ubuntu
With windows: clickphai click the link and select Properties in the directory location