Question

我有一个包含多个类的Java程序，所有这些类都扩展了JPanel（包含main方法的类除外）。我试图将int变量从一个类传递到另一个类，并使用一些先前提出的问题，提出了这个：

Class RollPanel

    public int getbrainCount()
    {
    return brainCount;
    }

Class BrainsPanel（我试图发送变量的地方）

   void setbrainCount()
   {
   RollPanel rollpanel = new RollPanel();
   brainCount = rollpanel.getbrainCount();
   }

这并没有给出任何错误，但是当我将brainCount添加到标签以查看其值时，它总是为0.

brainCount在RollPanel的类级别声明，然后使用此代码在按钮侦听器中给出一个值：

        value1 = generator.nextInt(3) + 1;
        value2 = generator.nextInt(3) + 1;
        value3 = generator.nextInt(3) + 1;
        //rollTotal++;

        //Counts how many brains were rolled.
        if (value1 == 1)
            brainCount++;
        if (value2 == 1)
            brainCount++;
        if (value3 == 1)
            brainCount++;

据我所知，只是声明一个变量会自动意味着它的值一开始就为零（我假设这是为什么它显示为零），但我怎样才能在其后传递更新的值上面的代码到brainsPanel所以我可以将它的值添加到brainsPanel中的标签？ getBrainCount（）会在按钮监听器之后出现吗？我觉得我在这里忽略了一些简单的事情......

编辑：我认为问题不在于设定者，因为它是吸气剂。因为在RollPanel（getter是）中我将brainCount声明为int，其初始值为0，所以当getter获取值时，它始终保持为0，即使在按钮监听器中应更改brainCount。这是RollPanel的全部内容。如何让getter获取brainCount的更新值而不是其初始0？

package zombiedice;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;

public class RollPanel extends JPanel
{
JLabel die1Label, die2Label, die3Label, testLabel;
JButton rollButton, sortButton;
JPanel dicePanel, buttonPanel;
ImageIcon die1, die2, die3;
int rollTotal, value1, value2, value3;
int brainCount, blastCount;
Random generator = new Random();



public RollPanel()
{
    setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); 
    setBackground(Color.black);

    dicePanel = new JPanel();
    dicePanel.setBackground(Color.black);

    //Creates blank ImageIcons to be used later to display dice.
    die1 = new ImageIcon(); 
    die2 = new ImageIcon(); 
    die3 = new ImageIcon(); 

    //A panel just to hold the buttons.
    buttonPanel = new JPanel();

    //Creates and links roll button to RollListener.
    rollButton = new JButton("Roll");
    rollButton.addActionListener(new RollListener());
    buttonPanel.add(rollButton);

    //After a roll, this button will need to be clicked so brain and blast
    //die can be sorted into their proper catergories. 
    sortButton = new JButton("Sort");
    sortButton.addActionListener(new SortListener());


    //Creates labels out of the dice images.
    die1Label = new JLabel(die1);
    die2Label = new JLabel(die2);
    die3Label = new JLabel(die3);

    //Adds image labels to the panel that holds the dice.
    dicePanel.add(die1Label);
    dicePanel.add(die2Label);
    dicePanel.add(die3Label);

    add(dicePanel);
    add(buttonPanel);
} //Closes constructor



//Roll button listener.
private class RollListener implements ActionListener
{
    public void actionPerformed(ActionEvent event)
    {
        rollButton.setEnabled(false);
        repaint();
        buttonPanel.add(sortButton);
        repaint(); 
        sortButton.setEnabled(true);
        repaint();

        value1 = generator.nextInt(3) + 1;
        value2 = generator.nextInt(3) + 1;
        value3 = generator.nextInt(3) + 1;
        //rollTotal++;

        //Counts how many brains were rolled.
        if (value1 == 1)
            brainCount++;
        if (value2 == 1)
            brainCount++;
        if (value3 == 1)
            brainCount++;

        //Updates the dice
        die1Label.setIcon(new ImageIcon(value1 + ".png"));
        die2Label.setIcon(new ImageIcon(value2 + ".png"));
        die3Label.setIcon(new ImageIcon(value3 + ".png")); 



    } //Closes actionPerformed
} //Closes the listener for the roll button



//Sort button listener.
private class SortListener implements ActionListener
{
    public void actionPerformed(ActionEvent event)
    {
        sortButton.setEnabled(false);
        repaint();
        rollButton.setEnabled(true);
        repaint();



    } //Closes actionPerformed.

}//Closes sort button listener. 
public int getBrainCount()
{
return brainCount;
} 

} //Closes class

BrainsPanel

package zombiedice;
import javax.swing.*;
import java.awt.*;

public class BrainsPanel extends JPanel
{
ImageIcon icon1 = new ImageIcon();
ImageIcon icon2 = new ImageIcon();
JLabel brainTotal, label1, label2;
JPanel brainPanel;
int brainCount;


void setbrainCount(int count)
{
   // RollPanel rollpanel = new RollPanel();
   brainCount = count;
   //brainCount = count;
}

public BrainsPanel()
{


setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); 

setBackground(Color.black);


icon1 = new ImageIcon("1.png");
icon2 = new ImageIcon("1.png");
label1 = new JLabel(icon1);
label2 = new JLabel(icon2);
brainTotal = new JLabel ("Brains eaten: " + brainCount);

add(label1);
add(label2);
add(brainTotal);



} //Closes constructor
} //Closes class

Answer 1

在这个代码的和平中：

void setbrainCount() {
    RollPanel rollpanel = new RollPanel();
    brainCount = rollpanel.getbrainCount();
}

在获得RollPanel之前，您始终会创建一个新的brainCount对象。当然，如果它在RollPanel中声明为字段，则为0。变量是新初始化的，对象创建只是之前的行。

您应该确保始终使用相同的RollPanel对象，例如将其保留为BrainsPanel中的字段。用给定的代码很难肯定地说。

Answer 2

我相信你应该尝试以下方法：

void setbrainCount(RollPanel rollPanel)
{
    brainCount = rollpanel.getbrainCount();
}

这样您就不会尝试使用新初始化的值，该值始终为0.

Althozuh从技术上讲，只需发送计数并设置

就更有意义了

void setbrainCount(int brainCount)
{
    this.brainCount = brainCount;
}

将变量传递给另一个类（Java）

2 个答案: