How to add the input from a textfield

Question

Here is my code below, I will highlight what is throwing the error, I am completely lost on how to fix this...

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.awt.event.ActionListener.*;
import java.awt.event.TextListener.*;
public abstract class GradeAverage extends Applet
implements ActionListener, TextListener{
Button Ok=new Button("Ok");
Button Cancel=new Button("cancel");
TextField Math=new TextField("Math Grade",2);
TextField Science=new TextField("Scien Grade",2);
TextField SocialStudies=new TextField("Social Studies Grade",2);
TextField English=new TextField("English Grade",2);
TextField Elective=new TextField("Elective Grade",2);
TextField Elective2=new TextField("2nd Elective Grade",2);
TextArea message=new TextArea();
public void init(){
GridBagLayout gbl=new GridBagLayout();
setLayout(gbl);
GridBagConstraints c=new GridBagConstraints();
c.anchor=GridBagConstraints.WEST;
c.weightx=2.0;
c.weighty=2.0;
c.fill=GridBagConstraints.HORIZONTAL;
c.insets=new Insets(10,10,10,10);
gbl.setConstraints(Math,c); add(Math);
c.fill=GridBagConstraints.NONE;
gbl.setConstraints(Science,c); add(Science);
c.fill=GridBagConstraints.HORIZONTAL;
gbl.setConstraints(SocialStudies,c); add(SocialStudies);
c.gridy=1;
gbl.setConstraints(English,c); add(English);
c.gridy=2;
gbl.setConstraints(Elective,c); add(Elective);
c.fill=GridBagConstraints.NONE;
gbl.setConstraints(Elective2,c); add(Elective2);
c.gridy=3;
c.anchor=GridBagConstraints.CENTER;
gbl.setConstraints(Ok,c); add(Ok);
gbl.setConstraints(Cancel,c); add(Cancel);
c.gridy=4;
c.gridwidth=3;
c.fill=GridBagConstraints.BOTH;
gbl.setConstraints(message,c); add(message);
Math.addTextListener(this);
Science.addTextListener(this);
SocialStudies.addTextListener(this);
English.addTextListener(this);
Elective.addTextListener(this);
Elective2.addTextListener(this);
Ok.addActionListener(this);
Cancel.addActionListener(this);
}
public void actionPerformed(ActionEvent event){
Object Source=event.getSource();
if(Source==Ok){
Math.getText();
Science.getText();
SocialStudies.getText();
English.getText();
Elective.getText();
Elective2.getText();
do{ 
**message=(Math+Science+SocialStudies+English+Elective+Elective2)/6;**
system.println("Your grade average is"+message);
}while (message<0);
if(Source==Cancel){
system.ext(0);
}
}}}

The code throwing the error is marked by ** The error given is: bad operand types for binary operator '+'

Please help!

Thanks

score 2 · Accepted Answer · answered May 22 '13 at 23:58

You cannot add TextFields together, and Java does not support overloading. To get the value, you must first call getText() on each TextField, then pass it to Double.parseDouble to convert it into a number that Java can add.

You should have something like this:

double gpa = (Double.parseDouble(Math.getText()) +
              ...
              Double.parseDouble(Elective2.getText())
             ) / 6;

You'll need to catch NumberFormatException if any TextField contains text that can't be converted into a number.

Then you'll need to convert the GPA into text for the TextArea you've called message.

message.setText(String.valueOf(gpa));

Thank you very much! This worked, no more errors in my program, I kept trying things for hours before I posted here lol. Thank you!! — SpHrr, May 23 '13 at 00:09

score 0 · Answer 2 · edited May 23 '17 at 10:25

0

It looks like you are trying to add string variables together - try converting them to integer values first. something like

 message=(Integer.parseInt(Math)+Integer.parseInt(Science)+Integer.parseInt(English)...

Here is a link to another thread on this very subject: How to convert a String to an int in Java?

Hope this helps you!

edited May 23 '17 at 10:25

Community

1
1

answered May 22 '13 at 23:52

Thomas Fonseca

542
4
12

`Math`, `Science`, etc. are `TextFields` and not `Strings`. – rgettman May 23 '13 at 00:01

How to add the input from a textfield

2 Answers2