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java - 如何将输出队列放在 JTextArea 中？

问题描述

您好，我一直在尝试获取有关在 JTextArea 上获取队列输出的代码。已经4小时了，哈哈。我是一年级学生，请多多包涵。同样，目标是获得一个将输出到 JTextArea 的队列以及包含 Enqueue、Dequeue 和 Exit 的菜单栏。我已经在那里创建了一堆函数，以防我不得不用于即将到来的考试。

类队列：

import javax.swing.JOptionPane;
import javax.swing.JTextArea;
public class Queue {
    private int num[];
    private int front, rear, capacity;
    public int hold;
    public Queue() {
        capacity=5;
        num = new int[capacity];
        front=rear=1;
    }
    public Queue(int capacity) {
        this.capacity = capacity;
        num = new int[capacity];
        front=rear=-1;
    }
    public boolean isEmpty() {return rear==-1;}
    public boolean isFull() {return (rear == capacity -1);}
    
    private void errorMessage(String msg) {
        JOptionPane.showMessageDialog(null, msg, "Full", JOptionPane.ERROR_MESSAGE);
    }
    public void enqueue(int data) {
        if(isFull()) {
            errorMessage("Queue is Full!");
        }else {
            num[++rear] = data;
            front=0;
        }
    }
    public int dequeue() {
        int val = 0;
        if (isEmpty()) {
            errorMessage("Queue is Empty");
            front=-1;           
        }else {
            val=num[front];
            
            for(int i=0; i<rear; i++) {
                num[i]=num[i+1];
            }
            rear--;
        }
        return val;
    }
    public String display() {
        String hold="";
        if(!isEmpty()) {
            for(int i = front; i<=rear; i++) {
                hold+=num[i]+" ";
            }
        }else {
            hold="Queue is empty";
        }
        return hold;
    }
    public int peek() {
        if(isEmpty()) {
            System.err.println("Queue is empty");
            return -1;
        }else {
            return num[front];
        }
    }
    public int last() {
        if(isEmpty()) {
            errorMessage("Queue is empty");
            return -1;
        }else {
            return num[rear];
        }
        
        Object menu[]= {"Enqueue", "Dequeue", "Close"};
        select = JOptionPane.showInputDialog(null, new JTextArea(hold), 1, null, menu, menu[0].toString());

    }
    public int frontValue() {return num[front];}
    public int rearValue() {return num[rear];}
    public int getCurrentSize() { return capacity-(capacity-(rear+1));}
    public int getCapacity() {return capacity;} 
}

我目前的输出是这样的：

2
0
0 0 14 24 46 
0
0 14 24 46 
14
14 24 46

这是我的 ADTQueue：

    public class ADTQueue {

    public static void main(String[] args) {
        Queue q =new Queue();
        q.peek();
        System.out.println(q.getCurrentSize());
        System.out.println(q.last());
        q.enqueue(14);
        q.enqueue(24);
        q.enqueue(46);
        System.out.println(q.display());
        q.enqueue(16);
        System.out.println(q.dequeue());
        System.out.println(q.display());
        q.dequeue();
        System.out.println(q.peek());
        System.out.println(q.display());
    }

}

标签： java

解决方案

我修改了你的代码。如果发生故障，Queue应该以某种有意义的方式报告该故障，在这种情况下，我使用了自定义Exception.

您需要考虑的其他一些注意事项是

  1. 文本区域String仅支持内容，因此您需要转换输出
  2. 将文本附加到文本区域不会自动插入新行，因此您需要这样做。

请参阅如何使用文本区域

import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public final class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JTextArea textArea = new JTextArea(10, 20);

        public TestPane() {
            setLayout(new BorderLayout());
            add(new JScrollPane(textArea));
            Queue q = new Queue();
            q.peek();
            textArea.append(Integer.toString(q.getCurrentSize()) + "\n");
            textArea.append(Integer.toString(lastFrom(q)) + "\n");
            enqueue(q, 14);
            enqueue(q, 24);
            enqueue(q, 46);
            textArea.append(q.display() + "\n");
            enqueue(q, 16);            
            textArea.append(Integer.toString(dequeue(q)) + "\n");
            textArea.append(q.display());
            dequeue(q);
            textArea.append(Integer.toString(q.peek()) + "\n");
            textArea.append(q.display() + "\n");
        }

        public int lastFrom(Queue queue) {
            try {
                return queue.last();
            } catch (Queue.QueueException ex) {
                textArea.append("ERR: Failed get last value from queue\n");
                textArea.append("ERR: Queue is " + ex.getState() + "\n");
            }
            return -1;
        }

        public void enqueue(Queue queue, int value) {
            try {
                queue.enqueue(value);
            } catch (Queue.QueueException ex) {
                textArea.append("ERR: Failed to enqueue " + value + "\n");
                textArea.append("ERR: Queue is " + ex.getState() + "\n");
            }
        }

        public int dequeue(Queue queue) {
            try {
                return queue.dequeue();
            } catch (Queue.QueueException ex) {
                textArea.append("ERR: Failed to dequeue value");
                textArea.append("ERR: Queue is " + ex.getState() + "\n");
            }

            return -1;
        }

    }

    public class Queue {

        public class QueueException extends Exception {

            public enum State {
                FULL, EMPTY;
            }

            private State state;

            public QueueException(State state) {
                this.state = state;
            }

            public State getState() {
                return state;
            }

        }

        private int num[];
        private int front, rear, capacity;
        public int hold;

        public Queue() {
            capacity = 5;
            num = new int[capacity];
            front = rear = 1;
        }

        public Queue(int capacity) {
            this.capacity = capacity;
            num = new int[capacity];
            front = rear = -1;
        }

        public boolean isEmpty() {
            return rear == -1;
        }

        public boolean isFull() {
            return (rear == capacity - 1);
        }

        public void enqueue(int data) throws QueueException {
            if (isFull()) {
                throw new QueueException(QueueException.State.FULL);
            }
            num[++rear] = data;
            front = 0;
        }

        public int dequeue() throws QueueException {
            int val = 0;
            if (isEmpty()) {
                front = -1;
                throw new QueueException(QueueException.State.EMPTY);
            } else {
                val = num[front];

                for (int i = 0; i < rear; i++) {
                    num[i] = num[i + 1];
                }
                rear--;
            }
            return val;
        }

        public String display() {
            String hold = "";
            if (!isEmpty()) {
                for (int i = front; i <= rear; i++) {
                    hold += num[i] + " ";
                }
            } else {
                hold = "Queue is empty";
            }
            return hold;
        }

        public int peek() {
            if (isEmpty()) {
                System.err.println("Queue is empty");
                return -1;
            } else {
                return num[front];
            }
        }

        public int last() throws QueueException {
            if (isEmpty()) {
                throw new QueueException(QueueException.State.EMPTY);
            } else {
                return num[rear];
            }
        }

        public int frontValue() {
            return num[front];
        }

        public int rearValue() {
            return num[rear];
        }

        public int getCurrentSize() {
            return capacity - (capacity - (rear + 1));
        }

        public int getCapacity() {
            return capacity;
        }
    }
}

仅供参考：将来，您实际上需要提供尝试的演示。我差点走过这个问题

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