我已经查看了其他一些答案并找到了一些解决方案，我正在使用JTextArea.append（），但令我困惑的是我的实现在一个方法中工作，而不是另一个方法。
在我的框架类中，当我调用“open（）”并打开文件时，它使用getjTextArea1（）和
在jTextArea1中显示输出getjTextArea1().append("\n"+"Writing data to file..." + "\n"+Controller.stats());
然而，当我尝试做同样的事情（我认为它是相同的，但它不起作用，显然它不是），使用方法“display（）”它运行方法，但不附加jTextArea。
我是java的新手，我花了一些时间查看其他答案，但似乎无法理解为什么我的代码不起作用。
我有以下代码，应编译并作为最低示例运行。
主控制器类：
package forSO;
import java.awt.EventQueue;
import javax.swing.JFrame;
public class Controller {
public static Checkout till1;
public static void main(String[] args) throws Exception
{
EventQueue.invokeLater(new Runnable() {
public void run() {
new Frame().setVisible(true);
new Frame().setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
});
till1 = new Checkout();
till1.simulation();
}
public static String stats()
{
String maxLength=till1.CalculateMaxLength();
String stats = "Max length = "+maxLength;
return stats;
}
}
结帐类，模拟发生的地方：
package forSO;
import java.io.*;
import java.text.DecimalFormat;
import java.util.*;
public class Checkout{
private static int nTimeSteps = Frame.getnTimeSteps();
private static Queue<String> tillQueue;
private static int rndNumber;
private static int currentLen;
private static ArrayList <Integer> lengthList;
private int maxLength;
private static Random r;
public Checkout(){
tillQueue = new LinkedList<String>();
currentLen = 0;
lengthList = new ArrayList <Integer>();
r = new Random();
}
public void simulation(){
System.out.println("Time"+"\t"+"Rnd"+"\t"+"Queue Status");
int t = 1; //controller for timesteps
Frame fFrame = new Frame();
while (Frame.isRunning == true && t < nTimeSteps+1){
rndNumber = r.nextInt(6)+1; //Generate random number between 0-6
if (rndNumber==2 || rndNumber==4 || rndNumber==6){
tillQueue.add(String.valueOf(t));
currentLen++;
}
else if ((rndNumber==1 || rndNumber==3) && !tillQueue.isEmpty()){
tillQueue.remove();
currentLen--;
}
else if(rndNumber==5){
}
//Printing the queue.
if (tillQueue.isEmpty()){
System.out.print(t+"\t"+rndNumber+"\t"+"Empty"+"\t");
}
else if (!tillQueue.isEmpty()){
System.out.print(t+"\t"+rndNumber+"\t"+tillQueue.toString()+"\t");
}
//add currentLen to ArrayList for statistics
lengthList.add(new Integer(currentLen));
//print out the statistics after first updating the arraylist
System.out.println(Controller.stats());
/**
*########################################################################
*This is where I make the call to the display() method and where I EXPECT
*to see the stats data printed to my JTextField
*########################################################################
*/
fFrame.display();
//slow down the simulation rate
try
{
Thread.sleep(200);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
//increment timesteps
t++;
}
}
//Normally there would be a lot of calculation for variance/standard dev,
//but I've limited it to just the max length to give an example.
public String CalculateMaxLength()
{
maxLength=0;
for (int i=0; i<lengthList.size(); i++)
{
int c = (Integer)lengthList.get(i).intValue();
if (maxLength < c)
{
maxLength = c;
}
}
String maxLengthString = new DecimalFormat("00").format(maxLength);
return maxLengthString;
}
public static boolean saveStringToFile(String fileName, String saveString)
{
boolean saved = false;
BufferedWriter bw = null;
try
{
bw = new BufferedWriter(new FileWriter(fileName, true));
try
{
bw.write(saveString); //write data to disk
saved = true;
}
finally
{
bw.close();
}
}
catch (IOException ex)
{
ex.printStackTrace(); //Print Exceptions
}
return saved; //true if the data was saved
}
}
框架类，我在其中创建JTextArea并尝试使用结帐类中的数据填充它
package forSO;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import javax.swing.GroupLayout;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.LayoutStyle;
import javax.swing.WindowConstants;
public class Frame extends JFrame {
private static final long serialVersionUID = 1L;
public Frame() {
super("Pro Checkout Simulator 2014");
initMenu();
initComponents();
}
private void initMenu(){
//Menu bar
menubar = new JMenuBar();
this.setJMenuBar(menubar);
saveItem = new JMenuItem("Save");
saveItem.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae)
{
//save file code
saveFile();
}
});
exitItem = new JMenuItem("Exit");
exitItem.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae){
System.exit(0);
}
});
//file menu
fileMenu = new JMenu("File");
menubar.add(fileMenu);
fileMenu.add(saveItem);
fileMenu.add(exitItem);
}
private void initComponents(){
p1 = new JPanel();
p4 = new JPanel();
p5 = new JPanel();
jScrollPane1 = new JScrollPane();
setjTextArea1(new JTextArea());
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
GroupLayout p4Layout = new GroupLayout(p4);
p4.setLayout(p4Layout);
p4Layout.setHorizontalGroup(
p4Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(p4Layout.createSequentialGroup()
.addContainerGap()
.addContainerGap())
);
p4Layout.setVerticalGroup(
p4Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(p4Layout.createSequentialGroup()
.addContainerGap()
.addContainerGap(GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
p5.setLayout(new BorderLayout());
jScrollPane1.setAutoscrolls(true);
getjTextArea1().setColumns(20);
getjTextArea1().setLineWrap(true);
getjTextArea1().setRows(5);
getjTextArea1().setMinimumSize(new java.awt.Dimension(100, 100));
getjTextArea1().setEditable(false);
jScrollPane1.setViewportView(getjTextArea1());
p5.add(jScrollPane1, BorderLayout.CENTER);
GroupLayout layout = new GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(p1, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(p4, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(layout.createSequentialGroup()
.addComponent(p5, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGap(6, 6, 6)))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(p1, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap()
.addComponent(p5, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addPreferredGap(LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(p4, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addContainerGap())
);
pack();
}
public static int getnTimeSteps() {
return nTimeSteps;
}
static boolean isRunning = true;
public void saveFile()
{
int result = fc.showSaveDialog(this);
if (result == JFileChooser.APPROVE_OPTION)
{
File myfile = fc.getSelectedFile();
//save file stuff
super.setTitle("Saved "+myfile.getAbsolutePath());
getjTextArea1().append("\n"+"Writing data to file..." + "\n"+Controller.stats());
Checkout.saveStringToFile(myfile.getAbsolutePath(),"\n"+Controller.stats());
}
else
{
super.setTitle("Cancel file save");
}
}
public void display()
{
getjTextArea1().append("This text should appear within the GUI window");
System.out.println("If you can see this, display() is being called");
getjTextArea1().append(Controller.stats());
}
public JTextArea getjTextArea1() {
return jTextArea1;
}
public void setjTextArea1(JTextArea jTextArea1) {
this.jTextArea1 = jTextArea1;
}
// Declare variables
public static int nTimeSteps = 10;
public static int addSliderValue;
public static int subSliderValue;
private JMenu fileMenu;
private JMenuBar menubar;
private JMenuItem saveItem,exitItem;
private JFileChooser fc = new JFileChooser();
private JPanel p1;
private JPanel p4;
private JPanel p5;
private JScrollPane jScrollPane1;
private JTextArea jTextArea1;
}
答案 0 :(得分：2)
我在您的代码中计算了五个单独的实例Frame，其中我认为只有一个是可见的，通常不是您正在与之交互的实例...
// 1...
public class Controller {
public static Frame myFrame = new Frame();
// 2, 3...
public static void main(String[] args) throws Exception
{
EventQueue.invokeLater(new Runnable() {
public void run() {
new Frame().setVisible(true);
new Frame().setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
});
// 4...
public class Checkout{
Frame testFrame = new Frame();
// 5...
public void simulation(){
//...
Frame fFrame = new Frame();
将其减少为一个并单独使用。这可能意味着您需要将框架的引用传递给应用程序的其他部分。
更好的解决方案是构建某种模型，它可以触发通知，告诉感兴趣的各方模型的某些部分已经改变，任何依赖于它的数据都应该更新....