Convert JTextField input into an Integer

问题

I am new to JAVA, I am trying to convert an input from a JTextField into an integer, I have tried loads of options but nothing is working, the eclipse is always giving me an error and the errors are not making sense to me.

import java.awt.Graphics; import java.awt.Color;

public class circle extends Shape{

public int x;
public int y;
public int Radius;

public circle (int Radius, int x, int y, Color c){
    super(c);
    this.x = x;
    this.y = y;
    this.Radius = Radius;
}
    public void draw(Graphics g){
        g.setColor(super.getColor());
        g.fillOval(x-Radius, y-Radius, Radius * 2, Radius * 2);
    }
 }

回答1:

In place of:

JTextField f1 = new JTextField("-5");

//xaxis1 = Integer.parseInt(f1);

try this:

JTextField f1 = new JTextField("-5");
String text = f1.getText();
int xaxis1 = Integer.parseInt(text);

You cannot parse TextField to Integer, but you can parse its value contained - text.

回答2:

You have two main errors that immediately leap to mind:

First you're trying to parse the JTextField itself, not the text it holds (as pointed out by dantuch -- 1+ to him).
Next, even if you were to successfully parse the text held by the JTextField, doing so at this point in your program is not productive since you'd be doing it at the time of JTextField creation, and would not have given the user a chance to change the values held by the fields.

A better solution would be to parse the text held by the JTextField, again as dantuch suggests, but to do so in a listener of some sort, perhaps an ActionListener that has been triggered by a JButton push.

回答3:

I've implemented number fields based on JFormattedTextField.

They also support a min and a max value.

Maybe you find them useful (the library is open source):

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JRealNumberField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JDoubleField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JFloatField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JLocalizedRealNumberField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JLocalizedDoubleField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JLocalizedFloatField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JWholeNumberField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JByteField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JIntegerField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JLongField.html

http://softsmithy.sourceforge.net/lib/docs/api/org/softsmithy/lib/swing/JShortField.html

Tutorial:

http://softsmithy.sourceforge.net/lib/docs/tutorial/swing/number/index.html

Homepage:

http://www.softsmithy.org

Download:

http://sourceforge.net/projects/softsmithy/files/softsmithy/

Maven:

<dependency>  
    <groupId>org.softsmithy.lib</groupId>  
    <artifactId>lib-core</artifactId>  
    <version>0.1</version>  
</dependency>

回答4:

You need to parse the value of the TextField:

int i = Integer.parseInt("-10");

Similarly

double d = Double.parseDouble("-10.0");

etc...

来源：https://stackoverflow.com/questions/11071211/convert-jtextfield-input-into-an-integer

标签

java

string

parsing

jtextfield

japplet