嗨,我创建了一个带有循环的等待队列模拟,并且使GUI出现了问题,当用户单击运行按钮时,几秒钟之内都没有显示,例如10-15秒,然后整个输出显示在JTextArea中.我如何输出要添加到jtextarea的所有内容,例如在控制台中.我查找了一个名为SwingWorker的东西.但是不知道如何使用它.请任何帮助.
package Windows;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class Station implements ActionListener
{
private JTextArea userinput, useroutput;
private JScrollPane sbr_userinput, sbr_useroutput;
private JButton runButton, clearButton, homeButton;
//LinkedList Customer Queue created here.
public static Queue<String> line = new LinkedList<String> ();
private static String time; //time variable.
private static DateFormat dateFormat = new SimpleDateFormat("HH:mm:ss"); //DateFormat variable.
private int intervals;
private int cashiers;
private int processing_time;
public static void main(String[] args)
{
new Station();
}
public Station()
{
JFrame frame = new JFrame("[=] Train Station Simulation [=]");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(800, 400);
frame.setContentPane(GUI());
frame.setVisible(true);
}
public Container GUI()
{
JPanel totalGUI = new JPanel();
totalGUI.setLayout(new GridLayout(1, 2, 3, 3));
JPanel lPanel = new JPanel();
lPanel.setLayout(new GridLayout(2, 1, 3 , 3));
totalGUI.add(lPanel);
JPanel rPanel = new JPanel(new GridLayout(3, 1, 3 , 3));
totalGUI.add(rPanel);
userinput = new JTextArea("Welcome to Train Station Queue Simulation!!!" + "\n" +
"Enter the number of cashiers available HERE!!!!:" + "\n");
userinput.setEditable(true);
userinput.setLineWrap(true);
userinput.setWrapStyleWord(true);
lPanel.add(userinput);
useroutput = new JTextArea();
useroutput.setEditable(false);
useroutput.setLineWrap(true);
useroutput.setWrapStyleWord(true);
lPanel.add(useroutput);
sbr_userinput = new JScrollPane(userinput, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
sbr_userinput.setPreferredSize(new Dimension(300, 300));
lPanel.add(sbr_userinput);
sbr_useroutput = new JScrollPane(useroutput, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
sbr_useroutput.setPreferredSize(new Dimension(300, 300));
lPanel.add(sbr_useroutput);
runButton = new JButton("RUN");
runButton.addActionListener(this);
rPanel.add(runButton);
clearButton = new JButton("CLEAR");
clearButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
userinput.setText("");
useroutput.setText("");
System.out.println("cleared");
}
});
rPanel.add(clearButton);
homeButton = new JButton("HOME");
rPanel.add(homeButton);
totalGUI.setOpaque(true);
return totalGUI;
}
public void actionPerformed(ActionEvent e)
{
cashiers = Integer.parseInt(userinput.getText());
if (e.getSource() == this.runButton)
{
useroutput.append("CUSTOMERS ARE COMING !!!! !!!!" + "\n" + "\n");;
//Array of all the customer that will enter the queue.
String list[] = {"Naqi", "Monty", "Mohin", "Yasmin", "Maighjoo", "Ashish", "Paal", "Kevin", "Ruhail", "Tony"};
//2nd ArrayList which customer are added to and removed later on so no duplicates arise.
ArrayList<String> customer = new ArrayList<String>(Arrays.asList(list));
int array_customer_list = list.length; //Recording the number of customers in the array.
//While statement containing for loop add customers to the empty LinkedList object.
while (line.isEmpty())
{
for (int x = 0; x < array_customer_list; x++ )
{
try
{
Thread.sleep(ran_interval() * 1000); //Sleep method to hold the arrival time by 1-2 seconds.
int cus = (int) (Math.random() * customer.size()); //Random customer is picked here.
String new_cus = customer.get(cus); //New customer object is created ere.
line.add(new_cus); //Customer objects are added to the empty LinkedList queue.
customer.remove(cus);
//For loop statement to outputting the queue.
for (String s : line)
{
useroutput.append("[" + s.toString() + " " + "]" + "\n");; //Outputting each customer and using the ".name" method so customers are readable.
}
//Outputting the whole queue and stating who has joined the queue.
useroutput.append("\n" + "The queue has " + line.size() + " customers so far" + "\n" +
new_cus.toString() + " Has Joined the Queue " + " <=== WAITING" + "\n" + "\n");
}
catch(Exception a) //ERROR handler for sleep method.
{
System.out.println("Intervals error: " + e); //Outputting the ERROR message.
System.exit(0); //If ERROR found exit system.
}
}
}
userinput.append("\n");
useroutput.append("CUSTOMERS ARE WAITING !!!! !!!!" + "\n" + "\n");
useroutput.append("Processing START !!!!" + "\n" + "\n");
while (!line.isEmpty()) //While statement with for loop to remove each customer from LinkedList queue.
{
try
{
String cus = line.remove(); //Method to remove customer from LinkedList queue.
String time = getTime();
Thread.sleep((processing_time() * 1000) / cashiers); //Sleep method to hold the processing by 1-3 seconds.
for (String s : line)
{
useroutput.append("[" + s.toString() + " " + "]" + "\n"); //Outputting each customer and using the ".name" method so customers are readable.
}
//Outputting the whole queue and stating who has joined the queue.
useroutput.append("\n" + "The queue has " + line.size() + " customers left" + "\n" +
cus.toString()+ " waited for " + time + " <=== SERVED" + "\n" + "\n");
}
catch(Exception a) //ERROR handler for sleep method.
{
System.out.println("Cashiers_wait error: " + e); //Outputting the ERROR message.
System.exit(0); //If ERROR found exit system.
}
}
}
useroutput.append("Processing FINISHED !!!!" + "\n");
System.out.println("working");
}
static String getTime() //Time Constructor
{
Calendar cal = Calendar.getInstance();
time = dateFormat.format(cal.getTime()); //Getting the current system time.
return time; //Return time.
}
public int ran_interval()
{
Random rand = new Random(); //Random object created here.
int interval = this.intervals = rand.nextInt(2) + 1; //Random number between 1-2 is generated for customer arrival here.
return interval;
}
public int processing_time()
{
Random ran = new Random(); //Random object created here.
int time = this.processing_time = ran.nextInt(4) + 1; //Random number between 1-3 is generated for customer arrival here.
return time;
}
}
解决方法:
Swing是一个单线程框架.也就是说,所有与UI的交互都应在事件调度线程的上下文内执行.
EDT的职责之一是处理重涂请求.
任何阻止此线程的进程都将阻止其更新UI.
在actionPerformed方法中,您正在EDT中运行一个耗时的过程,这就是为什么要花一些时间才能看到结果
Yu可以启动第二个线程并在那里处理数据,从而使EDT继续响应更新请求.问题是,Swing还要求对UI的任何修改也必须在EDT内部执行.
幸运的是,这里有一个简单的解决方案.
最好的选择是使用SwingWorker.它具有doInBackground方法,该方法使您可以在EDT上进行处理；一个发布方法,使您可以将结果发送回EDT；一种处理方法,用于处理正在发布的内容,该方法在EDT中执行；而done方法可以当doInBackground方法存在时,在EDT的上下文中调用
看看Concurrency in Swing了解更多详细信息