count button clicks

问题

I want to count the number of times the button is clicked using GUI.

I did this code:

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) 
 {                                         
  int clicked = 0;
  clicked++;
  System.out.println(clicked);
 }    

But it showing the output "1", each time I click the button.

I want every time I click the button to show me the count.

ex: If I click the button two times it should give me output of "2".

回答1:

You are resetting the counter every time you click, because you have defined the variable inside the action method. Try not doing that.

int clicked = 0; // move this outside
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) 
{                                         
    // int clicked = 0; -- this resets it to 0 each time
    clicked++;
    System.out.println(clicked);
}

回答2:

You've declared clicked as a local variable, initialised to 0, it can never be anything else but 1

Make clicked a class level variable instead...

private int clicked = 0;

//...

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) 
{                                         
    clicked++;
    System.out.println(clicked);
} 

回答3:

Try below code

int clicked = 0;
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) 
 {                                         

  clicked++;
  System.out.println(clicked);
 } 

回答4:

Change

int clicked = 0;

to be a member of your class. This way it wont be set to zero every time you press the button.

回答5:

You have declared count variable inside the ActionListener. Declare it outside the block.

int clicked = 0;  //make it as your class member.
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) 
{                                         

  clicked++;
  System.out.println(clicked);
}    

回答6:

Depending on how you are instantiating this class you need to declare the clicked variable at either the field level or the class variable level. Currently, the scope of the clicked variable is local to the method.

Option 1

int clicked = 0;

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) 
 {                                         
  clicked++;
  System.out.println(clicked);
 }  

Option 2

static int clicked = 0;

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) 
 {                                         
  clicked++;
  System.out.println(clicked);
 } 

The option you use will depend on instantiation. The second option should be avoided if possible.

回答7:

every time jButton1ActionPerformed fires, the clicked variables gets instantiated back to 0 that's why it is always giving you a value of 1. You should move the clicked variable outside of that method

//Somewhere in your class
private intClicked = 0;
//More methods here.

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) 
 {                                         
  clicked++;
  System.out.println(clicked);
 }

回答8:

import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;


public class Threading extends JFrame {

    private JPanel contentPane;
    private JTextField DisplayOne;
    private JTextField DisplayTwo;

    int count;
    int count1;
    int count2;


    /**
     * Launch the application.
     */

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() 
            {
                  try {
                    Threading frame = new Threading();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */


    public Threading() 
    {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        JPanel panel = new JPanel();
        contentPane.add(panel, BorderLayout.CENTER);

        DisplayOne = new JTextField();
        panel.add(DisplayOne);
        DisplayOne.setColumns(10);

        DisplayTwo = new JTextField();
        panel.add(DisplayTwo);
        DisplayTwo.setColumns(10);

        JButton btnCountOne = new JButton("Count 1");
        count1=0;
        btnCountOne.addActionListener(new ActionListener() {                
                public void actionPerformed(ActionEvent arg0) 
                {   
                    DisplayOne.setText(Integer.toString(count1++));
                }
        });
        panel.add(btnCountOne);

        JButton btnCountTwo = new JButton("Count 2");
        count2=0;
        btnCountTwo.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) 
            {
                DisplayTwo.setText(Integer.toString(count2++));
            }
        });
        panel.add(btnCountTwo);

        JButton btnCountBoth = new JButton("Count Both");
        count=0;
        btnCountBoth.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) 
            {
                while (count < 10)
                {
                DisplayOne.setText(Integer.toString(++count));
                DisplayTwo.setText(Integer.toString(count));
                }
            }
        });
        panel.add(btnCountBoth);
    }

}

来源：https://stackoverflow.com/questions/14999392/count-button-clicks