Question

我试图运行一个带有优先级队列系统的调度程序示例。它的工作原理如下：

使用包含优先级的GUI输入新进程。 GUI命令也终止进程。上下文切换是按命令进行的，因为切换的原因并不重要。代码中使用了三个组件，包括：基于优先级的就绪队列，阻止列表以及在每个上下文切换显示就绪，阻止和运行进程后输出完整系统状态。

import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.PriorityQueue;
import java.util.Queue;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
class dispatcher extends JFrame implements ActionListener {
    static int processNo = 0;
    static Process currentlyRunning;
    static Queue<Process> readyQueue;
    static Queue<Process> blockedQueue;
    static JButton newProcess;
    static JButton contextSwitch;
    static JTextField priority;
    static JTextArea Queues;

    private static Process newProcess(int i, int i0, String running) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
    dispatcher() {
        Container cp = getContentPane();
        cp.setLayout(new FlowLayout());
        Queues = new JTextArea(5, 15);
        Queues.setPreferredSize(new Dimension(500, 400));
        cp.add(Queues);
        cp.add(new JLabel("Priority"));
        priority = new JTextField(6);
        newProcess = new JButton("Create Process");
        newProcess.addActionListener(this);
        cp.add(priority);
        cp.add(newProcess);
        contextSwitch = new JButton("Context Switch");
        contextSwitch.addActionListener(this);
        cp.add(contextSwitch);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("Dispatcher");
        setSize(600, 500);
        setVisible(true);
    }
    public static void main(String args[]) {
        dispatcher d = new dispatcher();
        readyQueue = new PriorityQueue<>();
        blockedQueue = new PriorityQueue<>();
        Process p1 = newProcess(processNo++, 2, "Running");
        Process p2 = newProcess(processNo++, 1, "Blocked");
        Process p3 = newProcess(processNo++, 4, "Ready");
        Process p4 = newProcess(processNo++, 3, "Ready");
        Process p5 = newProcess(processNo++, 5, "Ready");
        Process p6 = newProcess(processNo++, 8, "Blocked");
        readyQueue.add(p3);
        readyQueue.add(p4);
        readyQueue.add(p5);
        blockedQueue.add(p6);
        blockedQueue.add(p2);
        currentlyRunning = p1;
        contextSwitch();
    }
    static void createProcess(int priority) {
        readyQueue.add(newProcess(processNo++, priority, "ready"));
    }
    static void contextSwitch() {

        String sb;
        String currentState = null;
        sb = "   " + currentlyRunning
                + "Currently Running Process"+"\n"
                + "Process No      Priority Current State\n"
                + currentlyRunning+processNo
                + "    "+currentlyRunning+priority+currentState + "\n\n";
        currentState = "Blocked";
        blockedQueue.add(currentlyRunning);
        currentlyRunning = readyQueue.poll();
        currentState = "Running";
        sb = sb + "Ready Queue\n" + "Process No   Priority Current State\n";
        for (Process p : readyQueue) {
            sb = sb + p+processNo + "   " + p+priority + "   " + p+currentState
                    + "\n\n";
        }
        sb = sb + "\nBlocked Queue\n" + "Process No Priority Current State\n";
        for (Process p : blockedQueue) {
            sb = "\n"
                    + sb + p+processNo + "   " + p+priority + "   " + p+currentState;
            Queues.setText(sb);
        }
    }
    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == newProcess) {
            System.out.print("process");
            int p = Integer.parseInt(priority.getText());
            p = (p < 0) ? 2 : p;
            createProcess(p);
        } else{
            System.out.print("context");
            contextSwitch();
        }
    }
}

输出应该是这样的：click here 但是我得到了这样一个空白的gui：click here 当我编译代码时，我得到了很多例外。如果我输入一个数字并单击任何按钮，我就会得到未知来源。但是没有在GUI中做任何事情，这就是堆栈跟踪：

Exception in thread "main" java.lang.UnsupportedOperationException: Not supported yet.
    at dispatcher.newProcess(dispatcher.java:24)
    at dispatcher.main(dispatcher.java:50)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

Answer 1

您的代码是

public static void main(String args[]) {
    dispatcher d = new dispatcher();
    readyQueue = new PriorityQueue<>();
    blockedQueue = new PriorityQueue<>();
    Process p1 = newProcess(processNo++, 2, "Running"); // <--- HERE
    ...

在标记的行上，您正在调用方法newProcess()。该方法目前被编码为抛出您所看到的异常。

private static Process newProcess(int i, int i0, String running) {
    throw new UnsupportedOperationException("Not supported yet.");
}

换句话说，您的代码正在完全按照您的要求执行操作。

要解决此问题，您必须编写newProcess()的代码。

具有优先级队列抛出异常的调度程序

1 个答案: