مشكلة في الاتصال بقواعد البيانات MySQL في اندرويد

لدي تطبيق يقوم بمحاولة بإنشاء اتصال بقواعد البيانات mysql ويظهر الخطأ التالي:

I/System.out: Error ************************java.sql.SQLNonTransientConnectionException: Could not create connection to database server.
W/System.err: java.lang.NullPointerException: Attempt to invoke interface method 'java.sql.Statement java.sql.Connection.createStatement()' on a null object reference
        at com.example.testjdbc.MainActivity.getUserList(MainActivity.java:54)
W/System.err:     at com.example.testjdbc.MainActivity.showData(MainActivity.java:73)
W/System.err:     at com.example.testjdbc.MainActivity.onCreate(MainActivity.java:24)
        at android.app.Activity.performCreate(Activity.java:7136)
W/System.err:     at android.app.Activity.performCreate(Activity.java:7127)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

الكود:

private Connection getConnection(){
        Connection con;
        try{
            Class.forName("com.mysql.cj.jdbc.Driver").newInstance();
            con = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/testandroid?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=CONVERT_TO_NULL&serverTimezone=GMT","root","");
            return con;
        }catch (Exception e){
            System.out.println("Error :"+e);
            return null;
        }
    }
    private ArrayList<User> getUserList()
    {
        ArrayList<User> userList = new ArrayList<>();
        Connection connection = getConnection();
        String query = "Select pseudo FROM `users` where userID="+1;
        Statement st;
        ResultSet rs;
        try{
            st =  connection.createStatement();
            rs = st.executeQuery(query);
            User user ;
            while (rs.next())
            {
                user = new User(rs.getString("pseudo"));
                userList.add(user);
            }
        }catch (Exception e){
            e.printStackTrace();
        }
        return userList;
    }
    private void showData(){
        ArrayList<User> list = getUserList();
        for (int i=0; i<list.size(); i++){
            test.setText(list.get(i).getPseudo());
            test.setText("gn");
        }
    }