我想在我的主面板中添加一个JComboBox，然后用ArrayList填充rectSizeList我用另一个名为ArrayList的方法（现在打印actionPerformed到控制台），此方法从另一个名为 /*
* Like so
*
*/
的静态方法获取其参数。在用户输入填充我的ComboBox之后，我无法找到一种方法来获取填充数组。任何帮助将不胜感激。
所有评论都是这种格式有助于提问：
import javax.swing.*;
public class ductulatorApp
{
public static void main(String[] args)
{
JFrame frame = new DuctulatorFrame();
frame.setVisible(true);
}
}
所有其他评论都是为了帮助我想要编译和运行的任何人，以便他们可以了解正在发生的事情。
主要课程
import javax.swing.*;
import java.awt.*;
public class DuctulatorFrame extends JFrame
{
private static final long serialVersionUID = 1L;
public DuctulatorFrame()
{
setTitle("Test Scores");
setSize(267, 200);
centerWindow(this);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new DuctulatorPanel();
this.add(panel);
}
private void centerWindow(Window w)
{
Toolkit tk = Toolkit.getDefaultToolkit();
Dimension d = tk.getScreenSize();
setLocation((d.width-w.getWidth())/2, (d.height-w.getHeight())/2);
}
}
框架类
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.*;
import java.util.ArrayList;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
public class DuctulatorPanel extends JPanel implements ActionListener
{
private static final long serialVersionUID = 1L;
private JTextField staticTextField,
cfmTextField,
rductTextField,
sqductTextField;
private JLabel staticLabel,
cfmLabel,
rductLabel,
sqductLabel;
private JButton calculateButton,
exitButton,
clearButton;
private JComboBox ductSizes; //JComboBox instance
private String[] ductList; //Array to fill JComboBox
double staticP; //static pressure entered by user
double cfm; //cfm entered by user
double deSQ;
double de; //round duct diameter
double pi = 3.14;
double ca; //round duct surface area
double radious;
double sqrA; //rectangular duct area
//two sides of rectangular duct
double a = 4;
double b = 4;
String squareduct;
public DuctulatorPanel()
{
// Creates main panel for labels and text fields
JPanel displayPanel = new JPanel();
displayPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));
staticLabel = new JLabel("Static pressure:");
displayPanel.add(staticLabel);
staticTextField = new JTextField(10);
displayPanel.add(staticTextField);
cfmLabel = new JLabel(" CFM:");
displayPanel.add(cfmLabel);
cfmTextField = new JTextField(10);
displayPanel.add(cfmTextField);
rductLabel = new JLabel("Round Duct:");
displayPanel.add(rductLabel);
rductTextField = new JTextField(15);
rductTextField.setEditable(false);
rductTextField.setFocusable(false);
displayPanel.add(rductTextField);
sqductLabel = new JLabel("Square Duct:");
displayPanel.add(sqductLabel);
/*
* This is where I want to add my JComboBox problem is I want to populate ductList arr
* with the array inside rectSizeList(int number) BELOW
* right now this method only prints my array to the console
* this method takes its parameters from the value assigned to
* actionperformed(ActionEvent e)
* below is comboBox commented out
*/
//ductList = new String[list.size]; THIS IS ASSUMING I COULD SOME HOW TRANSFER
//ductList = list.toArray(ductList); ARRAYLIST UP HERE AND NAME IT LIST AND USE IT
//ductSizes = new JComboBox(ductList);
//ductSizes.setSelectedIndex(1);
//displayPanel.add(ductSizes);
sqductTextField = new JTextField(10);
sqductTextField.setEditable(false);
sqductTextField.setFocusable(false);
displayPanel.add(sqductTextField);
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));
calculateButton = new JButton("Calculate");
calculateButton.addActionListener(this);
buttonPanel.add(calculateButton);
clearButton = new JButton("Clear");
clearButton.addActionListener(this);
buttonPanel.add(clearButton);
exitButton = new JButton("Exit");
exitButton.addActionListener(this);
buttonPanel.add(exitButton);
this.setLayout(new BorderLayout());
this.add(displayPanel, BorderLayout.CENTER);
this.add(buttonPanel, BorderLayout.SOUTH);
}
public void actionPerformed(ActionEvent e)
{
NumberFormat number = NumberFormat.getNumberInstance();
number.setMaximumFractionDigits(1);
Object source = e.getSource();
if(source == exitButton)System.exit(0);
else if(source == clearButton)
{
staticTextField.setText("");
cfmTextField.setText("");
rductTextField.setText("");
sqductTextField.setText("");
staticP = 0;
cfm = 0;
deSQ = 0;
}
else if(source == calculateButton)
{
try
{
staticP = Double.parseDouble(staticTextField.getText());
cfm = Double.parseDouble(cfmTextField.getText());
}
catch(NumberFormatException nfe)
{
staticTextField.setText("Invalid input");
staticP = 0;
cfm = 0;
deSQ = 0;
de = 0;
}
deSQ = staticP * (0.109136 * Math.pow(cfm, 1.9)); //Calculate round duct
de = Math.pow(deSQ, 0.199) * 2.5; //diameter
// Calculate round duct surface area
radious = de/2;
ca = (radious * radious) * pi;
ca = (int)ca;
rectSizeList((int)ca);
double i = 0;
for(i=0; i<ca; i++)
{
a = a + 0.5;
b = b + 0.5;
i = a * b; // convert round duct to rectangular duct
}
sqrA = i;
a = (int)a;
b = (int)b;
rductTextField.setText(number.format(de));
squareduct = (a + " x " + b);
sqductTextField.setText(squareduct);
}
}
public ArrayList<String> rectSizeList(int number)
{
if (number <= 0) throw new IllegalArgumentException("The number should be greater than 0.");
int i = 0;
int j = 0;
/*
* This is the array list I am hoping to use in order to fill array for
* comboBox
*/
ArrayList<String> rectangularDucts = new ArrayList<String>(); //Create array for rectangular duct
// Fill array for rectangular duct using nested for loop
/*
* If statement will ensure the result is with in range of surface
* area of duct
*/
for(i=4; i<=50; i++)
{
for(j=4; j<=50; j++)
{
if(number == i*j || (i*j)+1 == number || (i*j)-2 == number)
{
rectangularDucts.add(i + " x " + j);
}
}
if(number == i*j || (i*j)+1 == number || (i*j)-2 == number)
{
rectangularDucts.add(i + " x " + j);
}
}
System.out.println(rectangularDucts);
return rectangularDucts;
}
}
小组类
{{1}}
答案 0 :(得分：2)
我认为只用一个DefaultComboBoxModel对象，或者在你的情况下（我猜），一个DefaultComboBoxModel<String>对象就可以很容易地解决你的问题。给你的类这个字段，创建你的JComboBox作为它的模型，将它传递给构造函数，然后在需要时填充这个模型对象。
例如：
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.*;
public class ComboModelEg extends JPanel {
private DefaultComboBoxModel<String> comboModel = new DefaultComboBoxModel<>();
private JComboBox<String> comboBox = new JComboBox<>(comboModel);
private JTextField textField = new JTextField(5);
public ComboModelEg() {
// so combo box is wide enough
comboBox.setPrototypeDisplayValue(" ");
add(comboBox);
add(textField);
add(new JButton(new AddToComboAction("Add Text", KeyEvent.VK_A)));
}
// AbstractAction is like a *super* ActionListener
private class AddToComboAction extends AbstractAction {
public AddToComboAction(String name, int mnemonic) {
super(name); // button's text
putValue(MNEMONIC_KEY, mnemonic); // button's mnemonic key
}
@Override
public void actionPerformed(ActionEvent e) {
String text = textField.getText(); //get text from text field
comboModel.addElement(text); // and put it into combo box's model
}
}
private static void createAndShowGui() {
ComboModelEg mainPanel = new ComboModelEg();
JFrame frame = new JFrame("ComboModelEg");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
翻译成您的代码，它看起来像：
for (i = 4; i <= 50; i++) {
for (j = 4; j <= 50; j++) {
if (number == i * j || (i * j) + 1 == number
|| (i * j) - 2 == number) {
// rectangularDucts.add(i + " x " + j); //!!
comboModel.addElement(i + " x " + j); //!!
}
}
if (number == i * j || (i * j) + 1 == number || (i * j) - 2 == number) {
// rectangularDucts.add(i + " x " + j);
comboModel.addElement(i + " x " + j); //!!
}
}
答案 1 :(得分：0)
这就是我的工作方式
ArrayList<String> myList = new ArrayList<>();
//some code to populate the list
jComboBox.removeAllItems();
for(int i=0;i<myList.size();i++){
jComboBox.addItem(myList.get(i));
}