Lessons7Example1

package com.gmail.kudr641;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

public class Lessons7Example1 {

	public static void main(String[] args) {

		File file = new File("text.txt");

		Scanner scanner = new Scanner(System.in);

		try {
			file.createNewFile();
		} catch (IOException e) {
			e.printStackTrace();
		}

		System.out.println("Hello in PetrNotePad v0.1 enter your text if you want exit enter *exit*");
		String text = "";
		while (true) {
			String line = scanner.nextLine();
			text += line + System.lineSeparator();
			if (line.equals("exit")) {
				break;
			}			
		}
		
		saveTextFile(text, file);

		scanner.close();
	}

	static void saveTextFile(String text, File file) {

		try (PrintWriter pw = new PrintWriter(file)) {
			pw.println(text);
		} catch (IOException e) {
			System.out.println(e);
		}
	}
}

Lessons7Example2

package com.gmail.kudr641;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Random;
import java.util.Scanner;

public class Lessons7Example2 {

	public static void main(String[] args) {
		
		File file = new File("matrix.txt");

		try {
			file.createNewFile();
		} catch (IOException e) {

			e.printStackTrace();
		}
		
		int [][] matrix = createArray();
		
		String matrixString = "";
		for(int i = 0; i < matrix.length; i += 1){
			String line = Arrays.toString(matrix[i]) + System.lineSeparator();
			matrixString += line;			
		}
		saveTextFile(matrixString, file);
	}
	
	static int[][] createArray(){	
		Scanner scanner = new Scanner(System.in);
		
		System.out.println("Enter size matrix: ");
		int size = scanner.nextInt();
		
		Random random = new Random();
		
		int[][] matrix = new int[size][size];
			
		
		for(int i = 0; i < matrix.length; i += 1){
			for(int j = 0; j < matrix[i].length; j += 1){
				matrix[i][j] = random.nextInt(10);
			}
		}
		return matrix;
	}
	
	static void saveTextFile(String text, File file) {

		try (PrintWriter pw = new PrintWriter(file)) {
			pw.println(text);
		} catch (IOException e) {
			System.out.println(e);
		}
	}
}

Lessons7Example3

package com.gmail.kudr641;

import java.io.File;
import java.util.Scanner;

public class Lessons7Example3 {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);

		System.out.println("The distribution directory:");

		String directory = scanner.nextLine();

		scanner.close();

		directoryList(directory);
	}

	static void directoryList(String directory) {
		File file = new File(directory);
		File[] list = file.listFiles();
		for (int i = 0; i < list.length; i += 1) {
			if(list[i].isDirectory()){
				System.out.println(list[i]);
			}
		}
	}
}