Exercise no. 20

package lord1;

import javax.swing.JOptionPane;


public class carcontent {
  
    private boolean istrue;
  
    public carcontent()
    {
        istrue=true;
    }
  
    public void setgetistop(boolean stopistrue)
    {
        this.istrue=stopistrue;
    }
  
    public boolean getistop()
    {
        return istrue;
    }
  
    public static void main(String[]args)
    {
        carcontent set =new carcontent ();
     
        String choice="";
        double litre=0,maximum_gas=10,numberofgas=0,holddata=0,gascontent=0;
        int loop=0;
     
     
     
     
    do{
  
        choice=JOptionPane.showInputDialog(null,"R--->run  \nL--->Load gas  \nS--->stop car \nC--->gas content \nE--->exit");
        choice=choice.toUpperCase();
if(choice.equals("R")==true) 
{
  if(litre==0)
  {
    JOptionPane.showMessageDialog(null,"Gas is empty"); 
  }
  else if(litre<0.3 && litre!=0) 
  {
    JOptionPane.showMessageDialog(null,"Warning please refill it");
  }
  else if(litre==10)
  {
      JOptionPane.showMessageDialog(null,"Gas is full\nPlease proceed");
      set.setgetistop(false);
  }

  else
  {
      JOptionPane.showMessageDialog(null,"Car must stop");         
  }
}
if(choice.equals("L")==true)
{
    if(litre==10)
    {
        JOptionPane.showMessageDialog(null,"Gas is full");
    }
else
    {
  
    if(set.getistop()==true)
     {
     
     
      do{
          loop=0;
          numberofgas=Double.parseDouble(JOptionPane.showInputDialog(null,"The tank is full of fuel when it reaches 10 litres \nEnter number of gas"));
          holddata=litre+numberofgas;
          if(holddata > maximum_gas)
            {
             JOptionPane.showMessageDialog(null,"Please try again\n The maximum of gas content is 10 litre");         
             numberofgas=0;
             loop=1;
             }
         else
          {
            litre=litre+numberofgas;
           }
      }
        while(loop==1);
      }
    else
    {
         JOptionPane.showMessageDialog(null,"Car must stop"); 
    } 
}
}
if(choice.equals("S")==true) 
 {
     set.setgetistop(true);
   JOptionPane.showMessageDialog(null,"Car is stop"); 
 }
if(choice.equals("C")==true) 
{
    if(litre==0)
    {
         JOptionPane.showMessageDialog(null,"Gas content is: " + litre + "\n The car is not yet travel"); 
    }
    else
    {
    gascontent=Double.parseDouble(JOptionPane.showInputDialog(null,"Enter number of travel in km"));
    gascontent = gascontent * 0.5;
    litre=litre-gascontent;
    JOptionPane.showMessageDialog(null,"Gas content is: " + litre); 
    }
}
    }//do
    while(!choice.equals("E"));
    JOptionPane.showMessageDialog(null,"System terminated"); 
  
     
     
} 
}