我似乎无法弄清楚为什么我在运行此程序时填充了JTextArea。我曾经设置它来填充JTextArea中的项目，一旦使用点击开始按钮，由于某种原因我丢失了我的工作（不要问）。所以现在我想要运行它，但它总是填充。我试图设置JTextArea = null;但NetBeans希望我将文本区域设置为final。也许这就是问题所在。下面发布的是代码
public class InventoryGUI2 {
private static ArrayList<inventoryItem> inventory = new ArrayList<>();
public static void main(String[] args) {
makeWindow();
}
public static void makeWindow() {
final JTextArea outputText = new JTextArea(30,40);
JFrame newFrame = new JFrame();
//outputText = new JTextArea(30, 40);
newFrame.setSize(600, 600);
newFrame.setLocationRelativeTo(null);
Toolkit tk = Toolkit.getDefaultToolkit();
Dimension dim = tk.getScreenSize(); //get screen size from host OS
int xPos = (dim.width / 2) - (newFrame.getWidth() / 2); //Center the Screen horizontally
int yPos = (dim.height / 2) - (newFrame.getHeight() / 2); //center the screen vertically
newFrame.setLocation(xPos, yPos);
newFrame.setResizable(false);
newFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //set window to close once pressing the close button
newFrame.setTitle("Welcome"); //title of the window
JPanel thePanel = new JPanel(); //new panel
JLabel label1 = new JLabel("Inventory Program"); //label at the top of the window
thePanel.add(label1); //add the label to the panel
JButton startButton = new JButton("Start"); //create start button
startButton.setToolTipText("Start Program"); //set tooltip for start button
startButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent ae) {
outputText.append(inventory.toString());
}
}); //listen for actions on start button
// startButton.addActionListener(new ActionListener() {});
JButton exitButton = new JButton("Exit"); //create exit button
exitButton.setToolTipText("Exit Program"); //set tooltip for exit button
exitButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent ae) {
System.exit(0);
}
});
// outputText = new JTextArea(30, 40);
outputText.setLineWrap(true);
outputText.setWrapStyleWord(true);
JScrollPane scrollbar = new JScrollPane(outputText, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
thePanel.add(scrollbar);
newFrame.add(thePanel);
thePanel.add(startButton);
thePanel.add(exitButton);
newFrame.setVisible(true);
inventory.add(new inventoryItem("Pencil", 1111, 50, .25));
inventory.add(new inventoryItem("Pen", 2222, 50, 1.00));
inventory.add(new inventoryItem("Canned Air", 3333, 5, 2.00));
inventory.add(new inventoryItem("Notebook", 4444, 10, 2.50));
inventory.add(new inventoryItem("Staples", 5555, 5, 1.00));
inventory.add(new inventoryItem("Paper Clips", 6666, 100, .25));
inventory.add(new inventoryItem("Rubber Bands", 7777, 10000, .10));
inventory.add(new officeSupplyItem("Mechanical Pencil", 1112, 25, .50));
inventory.add(new officeSupplyItem("Lead Pencil", 1113, 25, .25));
inventory.add(new officeSupplyItem("Blue Pen", 2221, 25, 1.00));
inventory.add(new officeSupplyItem("Black Pen", 2223, 5, 1.00));
inventory.add(new officeSupplyItem("Red Pen", 2224, 20, 1.00));
inventory.add(new officeSupplyItem("Steno Notebook", 4441, 5, 2.50));
inventory.add(new officeSupplyItem("Legal Pad", 4442, 5, 2.50));
inventory = sortInventory(inventory);
for (int i = 0; i < inventory.size(); i++) {
inventory.get(i).output(outputText);
}
inventoryTotal(inventory, outputText);
sortInventory(inventory);
}
static ArrayList sortInventory(ArrayList<inventoryItem> unsorted) {
ArrayList<inventoryItem> sorted = new ArrayList<>();
inventoryItem alpha = null;
int lowestIndex = -1;
while (unsorted.size() > 0) {
for (int i = 0; i < unsorted.size(); i++) {
if (alpha == null) {
alpha = unsorted.get(i);
lowestIndex = i;
} else if (unsorted.get(i).itemName.compareToIgnoreCase(alpha.itemName) < 0) {
alpha = unsorted.get(i);
lowestIndex = i;
}
}
sorted.add(alpha);
unsorted.remove(lowestIndex);
alpha = null;
lowestIndex = -1;
}
return sorted;
}
static void inventoryTotal(ArrayList<inventoryItem> inventory, JTextArea outputText) {
double total = 0;
for (int i = 0; i < inventory.size(); i++) {
total = total + inventory.get(i).value;
}
String totalS;
totalS = String.valueOf((double) total);
outputText.append("Total value of inventory $" + totalS);
}
}
class inventoryItem { //Delcare variables below
String itemName;
String newUnit;
String newFee;
String newValue;
String newInventoryValue;
int itemNumber;
int inStock;
double unitPrice;
double value;
double restockingFee;
double inventoryValue;
public inventoryItem(String itemName, int itemNumber, int inStock, double unitPrice) { //declare variables for this class
this.itemName = itemName;
this.itemNumber = itemNumber;
this.inStock = inStock;
this.unitPrice = unitPrice;
restockingFee = .05 * value;
stockValue();
}
public void stockValue() {
value = unitPrice * inStock;
restockingFee = .05 * unitPrice;
inventoryValue = restockingFee + value;
newUnit = String.valueOf((double) unitPrice);
newFee = String.valueOf((double) restockingFee);
newValue = String.valueOf((double) value);
newInventoryValue = String.valueOf(inventoryValue);
}
public void output(JTextArea outputText) {
outputText.append("Item Name = " + itemName + " \n"); //print out the item name
outputText.append("Item Number = " + itemNumber + " \n"); //print out the item number
outputText.append("In Stock = " + inStock + " \n"); //print out how many of the item are in stock
outputText.append("Item Price = $" + newUnit + " \n"); //print out the price per item
outputText.append("Restocking fee is $" + newFee + " per item \n");
outputText.append("Value of item inventory = $" + newValue + " \n"); //calculate how much the inventory is worth for this one item
outputText.append("Cost of inventory including restocking fee = $" + newInventoryValue + " \n");
}
}
class officeSupplyItem extends inventoryItem {
double feeToRestock;
public officeSupplyItem(String itemName, int itemNumber, int inStock, double unitPrice) {
super(itemName, itemNumber, inStock, unitPrice);
feeToRestock = .05 * unitPrice;
}
@Override
public void output(JTextArea outputText) {
outputText.append("Item Name = " + itemName + " \n"); //print out the item name
outputText.append("Item Number = " + itemNumber + " \n"); //print out the item number
outputText.append("In Stock = " + inStock + " \n"); //print out how many of the item are in stock
outputText.append("Item Price = $" + newUnit + "\n"); //print out the price per item
outputText.append("Restocking fee is $" + newFee + " per item \n");
outputText.append("Value of item inventory = $" + newValue + " \n"); //calculate how much the inventory is worth for this one item
outputText.append("Cost of inventory including restocking fee = $" + newInventoryValue + "\n");
}
}
答案 0 :(得分：1)
主要方法调用makeWindow()。
makeWindow()来电inventory.get(i).output(outputText)和inventoryTotal(inventory, outputText)。
这两种方法写入文本区域：
outputText.append("Total value of inventory $" + totalS);
和
outputText.append("Item Name = " + itemName + " \n");
...
就这么简单。