我试图在点击下一个按钮后获取下一组值以显示在JTextFields中。我是编程新手，所以我不确定我错过了什么。我想要发生的是当我在窗口显示时点击下一个按钮时，下一组值现在将显示在相应的JTextField中，不幸的是，最终发生的事情是什么都没有。我已经尝试了几种不同的方法来实现这一点，到目前为止还没有。我知道它不是自己的按钮，因为如果我改变actionPerformed旁边说setTitle（“5000”）它将改变窗口内的标题。任何帮助表示赞赏。
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.*;
import java.util.Arrays;
import javax.swing.*;
import java.awt.*;
public class GUI extends JFrame implements ActionListener {
JButton next;
JButton previous;
JButton first;
JButton last;
private JLabel itmNum = new JLabel("Item Number: ", SwingConstants.RIGHT);
private JTextField itemNumber;
private JLabel proNm = new JLabel ("Product Name: ", SwingConstants.RIGHT);
private JTextField prodName;
private JLabel yr = new JLabel("Year Made: ", SwingConstants.RIGHT);
private JTextField year;
private JLabel unNum = new JLabel("Unit Number: ", SwingConstants.RIGHT);
private JTextField unitNumber;
private JLabel prodPrice = new JLabel("Product Price: ", SwingConstants.RIGHT);
private JTextField price;
private JLabel restkFee = new JLabel("Restocking Fee", SwingConstants.RIGHT);
private JTextField rsFee;
private JLabel prodInValue = new JLabel("Product Inventory Value", SwingConstants.RIGHT);
private JTextField prodValue;
private JLabel totalValue = new JLabel("Total Value of All Products", SwingConstants.RIGHT);
private JTextField tValue;
private double toValue;
int nb = 0;
char x = 'y';
public GUI()
{
super ("Inventory Program Part 5");
setSize(800,800);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLookAndFeel();
first = new JButton("First");
previous = new JButton("Previous");
next = new JButton("Next");
last = new JButton("Last");
first.addActionListener(this);
previous.addActionListener(this);
next.addActionListener(this);
last.addActionListener(this);
Movies[] titles = new Movies[9];
titles [0] = new Movies(10001, "King Arthur", 25 , 9.99, 2004, .05);
titles [1] = new Movies(10002,"Tron", 25, 7.99, 1982, .05);
titles [2] = new Movies(10003, "Tron: Legacy",25,24.99,2010,.05);
titles [3] = new Movies(10004,"Braveheart", 25,2.50,1995,.05);
titles [4] = new Movies(10005,"Gladiator",25,2.50,2000,.05);
titles [5] = new Movies(10006,"CaddyShack SE",25,19.99,1980,.05);
titles [6] = new Movies (10007,"Hackers",25,12.50,1995,.05);
titles [7] = new Movies (10008,"Die Hard Trilogy",25,19.99,1988,.05);
titles [8] = new Movies (10009,"Terminator",25,4.99,1984,.05);
Arrays.sort (titles, DVD.prodNameComparator);
itemNumber.setText(Double.toString(titles[nb].getitemNum()));
prodName.setText(titles[nb].getprodName());
year.setText(Integer.toString(titles[nb].getYear()));
unitNumber.setText(Integer.toString(titles[nb].getunitNum()));
price.setText(Float.toString(titles[nb].getprice()));
rsFee.setText(Double.toString(titles[nb].getRestkFee()));
prodValue.setText(Double.toString(titles[nb].getprodValue()));
tValue.setText("2636");
setLayout(new GridLayout(8,4));
add(itmNum);
add(itemNumber);
add(proNm);
add(prodName);
add(yr);
add(year);
add(unNum);
add(unitNumber);
add(prodPrice);
add(price);
add(restkFee);
add(rsFee);
add(prodInValue);
add(prodValue);
add(totalValue);
add(tValue);
add(first);
add(previous);
add(next);
add(last);
setLookAndFeel();
setVisible(true);
}
public void updateFields()
{
itemNumber.getText();
prodName.getText();
year.getText();
unitNumber.getText();
price.getText();
rsFee.getText();
prodValue.getText();
tValue.getText();
}
public void actionPerformed(ActionEvent evt){
Object source = evt.getSource();
if (source == next)
{
nb++;
}
}
private void setLookAndFeel()
{
try{
UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
SwingUtilities.updateComponentTreeUI(this);
} catch (Exception e) {
System.err.println("couln't use the system"+ "look and feel: " + e);
}
}
}
答案 0 :(得分：2)
您的ActionListener只有一个作业
nb = 1;
和repaint。这不会使用JTextFields数组Movies中的值更新titles。你需要明确地这样做。
itemNumber.setText(Double.toString(titles[nb].getItemNum()));
...
为了实现这一目标，您需要将Movies titles数组作为类成员变量，以便可以从ActionListener访问它。
此外，您实际上更改 nb中ActionListener的值。因为它是一个“下一个”按钮，你可能想要增加它：
nb++;
附注：
getitemNum getItemNum。ArrayList可以让您更灵活地在固定大小的数组上添加电影标题。答案 1 :(得分：1)
我认为chaning JTextFields的逻辑是在GUI类的构造函数中。因此，除非您正在创建GUI类的另一个对象，我可以看到它没有被创建。您的JTextFields不会更新。
所以基本上要解决这个问题，你必须移动你在另一个方法中更改JTextFields的逻辑，例如
public void updateFields(){
//place your logic code here
}
然后从actionPerformed方法调用此updateFields（）方法
public void actionPerformed(ActionEvent evt){
Object source = evt.getSource();
if (source == next)
{
nb =1;
}
updateFields();
///repaint(); /// you don't need the repaint method
}
根据您在评论中的问题，就我的理解而言，将您的titles数组放在构造函数之外，并执行以下更改，使其看起来像这样：
private JTextField tValue;
private double toValue;
int nb = 0; //note initialize this to 0
Movies[] titles = new Movies[9];//this is the line that comes out of the Constructor
public GUI()
{
///inside the constructor do the following changes
for (int i = 0; i < titles.length; i ++)
{
toValue += (titles[i].gettotalVal());
}
//note I will be accessing the 0th position of the array assuming you need the contents of the first objects to be displayed
itemNumber = new JTextField(Double.toString(titles[0].getitemNum()));
prodName = new JTextField(titles[0].getprodName());
year = new JTextField(Integer.toString(titles[0].getYear()));
unitNumber = new JTextField (Integer.toString(titles[0].getunitNum()));
price = new JTextField (Float.toString(titles[0].getprice()));
rsFee = new JTextField (Double.toString(titles[0].getRestkFee()));
prodValue = new JTextField(Double.toString(titles[0].getprodValue()));
tValue = new JTextField ("2636");
nb = 0;
//if (nb == 0) you don't need a if statement
//{
next.addActionListener(this);
//}
///现在用于updateFields（）方法
public updateFields(){
nb++;
itemNumber.setText(Double.toString(titles[nb].getitemNum());
prodName.setText(titles[nb].getprodName());
year.setText(Integer.toString(titles[nb].getYear()));
unitNumber.setText(Integer.toString(titles[nb].getunitNum()));
price.setText(titles[nb].getprice()));
rsFee.setText(Double.toString(titles[nb].getRestkFee()));
prodValue.setText(Double.toString(titles[nb].getprodValue()));
}