How can i invoke a void method in main?

Question

Hi guys I am killing myself over why we use void method if we can't call on it from main.
For example i am trying to create a program to calculate military time. In my main i am trying to call setHour which is void. setHour is supose to check if the input of hour is over 24 and if it is i have to reset hour to 00. But it gives an error that i can't call on that method because it is void.
So how do i invoke it from main?
and
Why do we use void if we can't call on it?
Thanks

Answer 1

ok here it is mate. It is not finished but pay attention on the setMethods that is what im trying to invoke from main. Here's my methods and then main will be under it.
public class MilitaryTime
      private int hour;
      private int minute;
      private int second;
       public MilitaryTime()
         hour=0;
         minute=0;
         second=0;
       public MilitaryTime(int hour, int minute, int second)
         this.hour=hour;
         this.minute=minute;
         this.second=second;
       public MilitaryTime(MilitaryTime t)
       public void setHour(int h)
         if(h>=24)
            h=00;
         else
            hour=h;
       public void setMinute(int m)
         if(m>=60)
            m=00;
         else
            minute=m;
       public void setSecond(int s)
         if(s>=60)
            s=00;
         else
            second=s;
       public int getHour()
         return hour;
       public int getMinute()
         return minute;
       public int getSecond()
         return second;
       public void tick()
         second=second+1;
       public String toUniversalString()
         StringBuffer     buffer;
         buffer = new StringBuffer();
      // add the hour (with leading zero if its neccesary)
         if(this.hour < 10)
            buffer.append("0");
         buffer.append(this.hour).append(":");
      // add the minute (with leading zero if its neccesary)
         if(this.minute < 10)
            buffer.append("0");
         buffer.append(this.minute).append(":");
      // add the second (with leading zero if its neccesary)
         if(this.second < 10)
            buffer.append("0");
         buffer.append(this.second).append("");
         return buffer.toUniversalString();
       public String toString()
         StringBuffer     buffer;
         buffer = new StringBuffer();
      // add the hour (with leading zero if its neccesary)
         if(this.hour < 10)
            buffer.append("0");
         buffer.append(this.hour).append(":");
      // add the minute (with leading zero if its neccesary)
         if(this.minute < 10)
            buffer.append("0");
         buffer.append(this.minute).append(":");
      // add the second (with leading zero if its neccesary)
         if(this.second < 10)
            buffer.append("0");
         buffer.append(this.second).append("");
         return buffer.toString();
   }Here is main where i try and call setHour to check for accuracy.
import javax.swing.*;
public class TestMilitaryTime
     public static void main(String[]args)
                    String sHour=JOptionPane.showInputDialog(null,
            "Input Hour:", "Military Time",JOptionPane.QUESTION_MESSAGE);
                    int hour=Integer.parseInt(sHour);
                    String sMinutes=JOptionPane.showInputDialog(null,
            "Input minutes:", "Military Time",JOptionPane.QUESTION_MESSAGE);
                    int minutes=Integer.parseInt(sMinutes);
                    String sSeconds=JOptionPane.showInputDialog(null,
            "Input seconds:", "Military Time",JOptionPane.QUESTION_MESSAGE);
                    int seconds=Integer.parseInt(sSeconds);
                    MilitaryTime time= new MilitaryTime(hour,minutes,seconds);
                    System.out.println(time.setHour());
                    System.out.println("The military time is you enterd is "+time.toString());
     Everything else works fine except the setHour thing.
Thanks