how to convert string into time format and add two hours

Question

I have the following requirement in the project.

I have a input field by name startDate and user enters in the format YYYY-MM-DD HH:MM:SS.

Answer 1

Basic program of adding two times:
You can modify hour:min:sec as per your need using if else.
This program shows you how you can add values from two objects and return in another object.

class demo
{private int hour,min,sec;
    void input(int hour,int min,int sec)
    {this.hour=hour;
    this.min=min;
    this.sec=sec;

    }
    demo add(demo d2)//demo  because we are returning object
    {   demo obj=new demo();
    obj.hour=hour+d2.hour;
    obj.min=min+d2.min;
    obj.sec=sec+d2.sec;
    return obj;//Returning object and later on it gets allocated to demo d3                    
    }
    void display()
    {
        System.out.println(hour+":"+min+":"+sec);
    }
    public static  void main(String args[])
    {
        demo d1=new demo();
        demo d2=new demo();
        d1.input(2, 5, 10);
        d2.input(3, 3, 3);
        demo d3=d1.add(d2);//Note another object is created
        d3.display();


    }

}

Modified Time Addition Program

 class demo
 {private int hour,min,sec;
    void input(int hour,int min,int sec)
    {this.hour=(hour>12&&hour<24)?(hour-12):hour;
    this.min=(min>60)?0:min;
    this.sec=(sec>60)?0:sec;

    }
    demo add(demo d2)
    {   demo obj=new demo();
    obj.hour=hour+d2.hour;
    obj.min=min+d2.min;
    obj.sec=sec+d2.sec;
    if(obj.sec>60)
    {obj.sec-=60;
        obj.min++;
    }
    if(obj.min>60)
    {   obj.min-=60;
        obj.hour++;
    }
        return obj;
    }
    void display()
    {
        System.out.println(hour+":"+min+":"+sec);
    }
    public static  void main(String args[])
    {
        demo d1=new demo();
        demo d2=new demo();
        d1.input(12, 55, 55);
        d2.input(12, 7, 6);
        demo d3=d1.add(d2);
        d3.display();


    }

 }