Only 2 decimal places!!!!

[joe kane]

I was wondering how do you, when returning a value that can have loads of decimal places how would you stop it at only two decimal places..
Thanks in advance joe kane

[Billybob Marshall]

See the javadocs for this class

[Thomas Paul]

I wrote an article about floating point numbers that shows some example of formatting decimals:
http://www.javaranch.com/newsletter/July2003/newsletterjuly2003.jsp#a4

[joe kane]

Thanks for the help, but im very new to java and im not too sure where the code goes for the decimal format...?

  
import javax.swing.JOptionPane;

public class Assignment1 {
    
    public static void main(String[] args) {
        
        // calls method
        start();
        
    }
    
    public static void start(){
        
        // declares all the vars...
        String choice1, choice9, choice2, choice3, choice;
        int one, two, three, tot1, tot2, tot3, totals;
        double num1, num2, num3;
        boolean between1And100 = false;
        
        //asign a value to a input box
        choice1 = JOptionPane.showInputDialog("Enter Grade 1");
        
        //if statement, if choice1 = ""
        if (choice1 == null){ System.exit(0);
        }
        
        // starts a do while loop, valadation for the input box
        while ( !choice1.matches("[0-9]+" ) ){
            
            //displys a message box with message
            JOptionPane.showMessageDialog(null,"Please enter number");
            
            //assigns choice1 to an input box.
            choice1 = JOptionPane.showInputDialog("Enter Grade 1");
        
        //loop the while loop
        }
        
        //assigns an integer value to choice1
        int value = Integer.parseInt(choice1);
        
        // starts an if statement valadating that the number entered is between 1 & 100
        if ((value >= 1) && (value <= 100))
            
            //assigns between1&00 to true
            between1And100 = true;
        
        // starts an if statement valadating that the number entered is between 1 & 100
        if ((value < 0) || (value > 100))
            
            //assigns between1&00 to true
            between1And100 = false;
        
        // starts a do while loop, valadation if between1&00 to false
        while (between1And100 == false){
            
            //displys a message box with message
            JOptionPane.showMessageDialog(null,"Grade is between 1 & 100");
            
            //assigns choice1 to an input box.
            choice1 = JOptionPane.showInputDialog("Enter Grade 1");
            
            //if statement, if choice1 = ""
            if (choice1 == null){ System.exit(0);}
            
            // starts a do while loop, valadation for the input box
            while ( !choice1.matches("[0-9]+" ) ){
                JOptionPane.showMessageDialog(null,"Please enter number");
                choice1 = JOptionPane.showInputDialog("Enter Grade 1");
                
            }
            
            //assigns choice1 as an integer
            value = Integer.parseInt(choice1);
            
            // starts an if statement valadating that the number entered is between 1 & 100
            if((value >= 1) && (value <= 100))
                
                //assigns between1&00 to true
                between1And100 = true;
            
            
        }
        
        //------------------------------------------------------------------------------
        
        choice2 = JOptionPane.showInputDialog("Enter Grade 2");
        
        //if statement, if choice1 = ""
        if (choice2 == null){ System.exit(0);  
        }
        
        // starts a do while loop, valadation for the input box
        while ( !choice2.matches("[0-9]+" ) ){
            JOptionPane.showMessageDialog(null,"Please enter number");
            choice2 = JOptionPane.showInputDialog("Enter Grade 2");
        }
        
        //assigns choice2 as an integer
        int value1 = Integer.parseInt(choice2);
        
        // starts an if statement valadating that the number entered is between 1 & 100
        if ((value1 >= 1) && (value1 <= 100))
            
            //assigns between1&00 to true
            between1And100 = true;
        
        // starts an if statement valadating that the number entered is between 1 & 100
        if ((value1 < 0) || (value1 > 100))
            
            //assigns between1&00 to true
            between1And100 = false;
        
        while (between1And100 == false){
            
            JOptionPane.showMessageDialog(null,"Grade is between 1 & 100");
            
            choice2 = JOptionPane.showInputDialog("Enter Grade 2");
            
            //if statement, if choice1 = ""
            if (choice2 == null){ System.exit(0);}
            
            // starts a do while loop, valadation for the input box
            while ( !choice2.matches("[0-9]+" ) ){
                JOptionPane.showMessageDialog(null,"Please enter number");
                choice2 = JOptionPane.showInputDialog("Enter Grade 2");
                
            }
            
            value1 = Integer.parseInt(choice2);
            
            // starts an if statement valadating that the number entered is between 1 & 100
            if((value1 >= 1) && (value1 <= 100))
                
                //assigns between1&00 to true
                between1And100 = true;
            
            
        }
        
        //------------------------------------------------------------------------------
        
        choice3 = JOptionPane.showInputDialog("Enter Grade 3");
        
        if (choice3 == null){ System.exit(0);
        }
        
        // starts a do while loop, valadation for the input box
        while ( !choice3.matches("[0-9]+" ) ){
            JOptionPane.showMessageDialog(null,"Please enter number");
            choice3 = JOptionPane.showInputDialog("Enter Grade 3");
        }
        
        int value2 = Integer.parseInt(choice3);
        
        // starts an if statement valadating that the number entered is between 1 & 100
        if ((value2 >= 1) && (value2 <= 100))
            
            //assigns between1&00 to true
            between1And100 = true;
        
        // starts an if statement valadating that the number entered is between 1 & 100
        if ((value2 < 0) || (value2 > 100))
            
            //assigns between1&00 to true
            between1And100 = false;
        
        
        while (between1And100 == false){
            
            JOptionPane.showMessageDialog(null,"Grade is between 1 & 100");
            
            choice3 = JOptionPane.showInputDialog("Enter Grade 3");
            
            if (choice3 == null){ System.exit(0);}
            
            // starts a do while loop, valadation for the input box
            while ( !choice3.matches("[0-9]+" ) ){
                
                
                JOptionPane.showMessageDialog(null,"Please enter number");
                choice3 = JOptionPane.showInputDialog("Enter Grade 3");
                
            }
            
            value2 = Integer.parseInt(choice1);
            
            // starts an if statement valadating that the number entered is between 1 & 100
            if((value2 >= 1) && (value2 <= 100))
                
                //assigns between1&00 to true
                between1And100 = true;
            
            
        }
        
        
        num1 = Double.parseDouble(choice1);
        
        num2 = Double.parseDouble(choice2);
        
        num3 = Double.parseDouble(choice3);
        
        double result1 = methodone(num1);
        
        double result2 = methodtwo(num2);
        
        double result3 = methodthree(num3);
        
        double finish = methodtotals(result1,result2,result3);
        
    }
    
//------------------------------------------------------------------------------
    
    public static double methodtotals(double x, double y, double z){
        
        String result1 = "" ;
        String x1 = "Pass";
        String x2 = "Merit";
        String x3 = "Fail";
        
        int result = ((int)(x + y + z));
        
        if (result > 49){
            
            result1 = x1;
        }
        if (result > 79){
            
            result1 = x2;
        }
        if (result < 49){
            
            result1 = x3;
        }
        
        int score = ((int)(x + y + z));
        
       
        
        JOptionPane.showMessageDialog(null,"Results  "+x+"/30  "+y+"/40  "+z+"/30  "+"\nTotal Result: "+score+"%/100\n Grade: "+ result1+"");
        start();
        return(x);
    }
    
    //------------------------------------------------------------------------------
    
    public static double methodone(double x){
        
        return (x * 0.3);
        
    }
    
    //------------------------------------------------------------------------------
    
    public static double methodtwo(double x){
        
        return (x * 0.4);
        
    }
    
    //------------------------------------------------------------------------------
    
    public static double methodthree(double x){
        
        return (x * 0.3);
        
        
    }}
//----------------------------------------------------------------------------------

Here is the program I have, it works 100%, it just needs the decimal format on 3 numbers,
Thanks loads in advance if you can help.....
Thanks joe Kane

[Thomas Paul]

Here is a simple program that shows how to format a float into a String with two deciamls:

import java.text.*;
public class JunkTest {

public static void main(String [] args) {
float f = 45.67f * 43.15f;
System.out.println(new DecimalFormat("0.00").format(f));
}
}

Notice that we need to import java.text as that is the package that the DecimalFormat class is in.