clear cin cout cpp

#include <iostream>
using namespace std;

int main()
{
string name = "";
cout << "enter your name: ";
getline(cin, name);
if (name.empty())
{
cout << "You should enter something ";
}
cout << "hello, " <<name << " you are user " <<endl;
return 0;

change fedora keymap

$ localectl status
To list available keymaps:

$ localectl list-keymaps
To set the default console keymap:

$ localectl set-keymap [keymap]
see man localectl for further information.

if you still don't have your keys try to:

setxkbmap -print -verbose 10

┌─[marek@localhost]─[~]
└──╼ setxkbmap -print -verbose 10
Setting verbose level to 10
locale is C
Trying to load rules file ./rules/evdev...
Trying to load rules file /usr/share/X11/xkb/rules/evdev...
Success.
Applied rules from evdev:
rules:      evdev
model:      pc104
layout:     us,pl
variant:    ,
Trying to build keymap using the following components:
keycodes:   evdev+aliases(qwerty)
types:      complete
compat:     complete
symbols:    pc+us+pl:2+inet(evdev)
geometry:   pc(pc104)
xkb_keymap {
xkb_keycodes  { include "evdev+aliases(qwerty)" };
xkb_types     { include "complete" };
xkb_compat    { include "complete" };
xkb_symbols   { include "pc+us+pl:2+inet(evdev)" };
xkb_geometry  { include "pc(pc104)" };
};

to change marked settings:

setxkbmap -layout xkb_layout

setxkbmap -model pc104 -layout cz,us -variant ,dvorak -option grp:alt_shift_toggle

Java scanner IO

import java.util.Scanner;
class helloworld
{
    public static void main (String[] args)
    {
        Scanner input = new Scanner(System.in);
        System.out.println("Enter name: ");
        String name = input.nextLine();
        System.out.println("Hello " +name);
    }
}

how to check db version - sql request JAVA

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;

public class dbConnection {

    public static void main(String[] args) {

        Connection con = null;
        Statement st = null;
        ResultSet rs = null;

        String url = "jdbc:mysql://localhost:3306/mysql";
        String user = "user";
        String password = "password";

        try {
            con = DriverManager.getConnection(url, user, password);
            st = con.createStatement();
            rs = st.executeQuery("SELECT VERSION()");

            if (rs.next()) {
                System.out.println(rs.getString(1));
            }

        } catch (SQLException ex) {
            Logger lgr = Logger.getLogger(dbConnection.class.getName());
            lgr.log(Level.SEVERE, ex.getMessage(), ex);

        } finally {
            try {
                if (rs != null) {
                    rs.close();
                }
                if (st != null) {
                    st.close();
                }
                if (con != null) {
                    con.close();
                }

            } catch (SQLException ex) {
                Logger lgr = Logger.getLogger(dbConnection.class.getName());
                lgr.log(Level.WARNING, ex.getMessage(), ex);
            }
        }
    }
}

remember about your jdbc driver:
mariadb-java-client-1.1.5.jar

IO - Java

Read from file:

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

public class fil{
public static void main(String[] args) throws FileNotFoundException{

File file = new File("/home/marek/workspace/java/myfile.txt");
System.out.print("Reading from file: " + file);
Scanner in = new Scanner(file);
String zdanie = in.nextLine();

System.out.println("\n: -> " + zdanie);

}


write to file:

import java.io.FileNotFoundException;
import java.io.PrintWriter;

public class save_to_file {
public static void main(String[] args) throws FileNotFoundException{
PrintWriter zapis = new PrintWriter("test.dat");
zapis.println("Marek Borkowski\n");
zapis.close();
System.out.println("success");
}
}

how to make jar

1. create manifest file - the name of the file should end with do .mf sufix

Manifest-Version: 1.0
Main-Class: hello

2. jar cmf manifest.mf hello.jar hello.class

3. to view the content of the JAR type:

jar tf jar_file.jar jar_file.class

4. to execute app:
java -jar jar_file.jar