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POHow to use variables defined in a public class in other classes in java?
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  1. POHow to use variables defined in a public class in other classes in java?
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    copied!<p>A layman's question on the definition and use of variables:</p> <p>I need to make a Java GUI that gets user's input and stores it within a text file. However this writing has to be done inside an Actionlistener class (ie, user is clicking the button and text file is created and stored). This means that I have to define a variable in one class (public class) and use it in another (the one that defines the Actionlistener).</p> <p>How can I do this? Are global variables the only way?</p> <p>In my code I first define 'textfield' as JTextField and then I want it to be read (as 'text') and stored (in 'text.txt').</p> <pre><code>import javax.swing.*; //... import java.io.BufferedWriter; public class Runcommand33 { public static void main(String[] args) { final JFrame frame = new JFrame("Change Backlight"); // ... // define frames, panels, buttons and positions JTextField textfield = new JTextField();textfield.setBounds(35,20,160,30); panel.add(textfield); frame.setVisible(true); button.addActionListener(new ButtonHandler()); } } class ButtonHandler implements ActionListener{ public void actionPerformed(ActionEvent event){ String text = textfield.getText(); textfield.setText(""); new BufferedWriter(new FileWriter("text.txt")).write(text).newLine().close(); // Afterwards 'text' is needed to run a command } } </code></pre> <p>When I compile I get</p> <pre><code>Runcommand33.java:45: error: cannot find symbol String text = textfield.getText(); ^ symbol: variable textfield location: class ButtonHandler </code></pre> <p>Without lines <em>String text =</em> to <em>new BufferedWriter</em> the code compiles.</p> <p>Note that I have tried the suggestions of this <a href="https://stackoverflow.com/questions/15999934/get-variable-in-other-classes">Get variable in other classes</a> and this <a href="https://stackoverflow.com/questions/10230274/how-do-i-access-a-variable-of-one-class-in-the-function-of-another-class">How do I access a variable of one class in the function of another class?</a> but they didn't work.</p> <p>Any suggestions?</p>
 

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