Java Method Call Expected

Question

This is a java program with two buttons used to change an integer value and display it. However in IntelliJIDEA the two lines with

increase.addActionListener(incListener());
decrease.addActionListener(decListener());

keep displaying errors 'Method call expected'.

I am not sure what to do to fix this.

Any help will be greatly appreciated

Thanks

Note: the full code is attached below.

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Main extends JDialog {
public JPanel contentPane;
public JButton decrease;
public JButton increase;
public JLabel label;

public int number;

public Main() {
    setContentPane(contentPane);
    setModal(true);

    increase = new JButton();
    decrease = new JButton();
    increase.addActionListener(incListener());
    decrease.addActionListener(decListener());

    number = 50;
    label = new JLabel();
}

public class incListener implements ActionListener {
    public void actionPerformed (ActionEvent event) {
        number++;
        label.setText("" + number);
    }
}

public class decListener implements ActionListener {
    public void actionPerformed (ActionEvent event) {
        number--;
        label.setText("" + number);
    }
}

public static void main(String[] args) {
    Main dialog = new Main();
    dialog.pack();
    dialog.setVisible(true);
    System.exit(0);

}
}

Instead of `incListener()` and `decListener()` make them `new incListener()` and `new decListener()`. — skuntsel, May 07 '13 at 11:47

score 22 · Accepted Answer · answered May 07 '13 at 11:47

22

incListener and declListener are classes, not methods.

Try

increase.addActionListener(new incListener());

btw, rename your classes names to make them start with an uppercase

answered May 07 '13 at 11:47

Arnaud Denoyelle

29,980
16
92
148

score 6 · Answer 2 · answered May 07 '13 at 11:48

6

It's simple: use new incListener() instead of incListener(). The later is trying to call a method named incListener, the former creates an object from the class incListener, which is what we want.

answered May 07 '13 at 11:48

PurkkaKoodari

6,703
6
37
58

score 1 · Answer 3 · answered May 07 '13 at 11:53

1

incListener and decListener are a classes but not a methods, so you must call new to use them, try this:

increase.addActionListener(new incListener()); decrease.addActionListener(new decListener());

sorry for my bad english

answered May 07 '13 at 11:53

Manitra

111
5

score 0 · Answer 4 · answered May 07 '13 at 11:47

0

substitute the lines with

increase.addActionListener( new incListener());
decrease.addActionListener( new decListener());

answered May 07 '13 at 11:47

Simulant

19,190
8
63
98

score 0 · Answer 5 · answered May 07 '13 at 11:55

Make these changes:

 public Main() {
    contentPane = new JPanel();
    setContentPane(contentPane);
    setModal(true);

    increase = new JButton("inc");
    decrease = new JButton("dec");
    contentPane.add(increase);
    contentPane.add(decrease);
    increase.addActionListener(new incListener());
    decrease.addActionListener(new decListener());

    number = 50;
    label = new JLabel(number+"");
    contentPane.add(label);
}

score 0 · Answer 6 · answered May 20 '19 at 17:56

0

It's sad but I had to Google this same error... I was staring at a method that returned a class. I left off the new operator.

return <class>(<parameters>) vs return new <class>(<parameters>)

answered May 20 '19 at 17:56

Cory

196
2
8

score -1 · Answer 7 · answered Jul 09 '18 at 20:03

Whenever a string object is created using new operator a new object is created which is what your program is looking for. The following link is useful in learning about the difference between a string and a new string. What is the difference between "text" and new String("text")?

Java Method Call Expected

7 Answers7

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