java - 编译后不显示GUI

Question

我目前正在开发一个地址簿程序，并且之前已经让它工作了......但由于某种原因，我无法在 DrJava 上打开 GUI 窗口

我尝试编译它，没有错误。我确实注释掉了异常，因为它给我带来了问题，所以我将修复该错误，但无论如何这是针对 FileIO 的

奇怪的是我无法弹出 GUI，我真的不知道为什么它不起作用......

    //imports
import javax.swing.*;
import java.io.PrintWriter;
import java.io.File;
import java.io.*;
import java.util.Scanner;
import java.awt.*;
import java.awt.event.*; //Adding the event since we will now be using an action listener
import java.io.FileNotFoundException;


public class AddressbookFinal extends JFrame implements ActionListener//actionlistener enables us to set actions to buttons 
{
    // Create some Panels
    JPanel pan1 = new JPanel ();//panel 1
    JPanel pan2 = new JPanel ();//panel 2
    File writeFile = new java.io.File ("Address book.txt"); //create the file to write to
    File readFile = new java.io.File ("Address book.txt");//read the file 
    //global variables 
    static final int MAX = 100;//lenght of the arrays
    String lastname[] = new String [MAX];//holds last names 
    String names[] = new String [MAX];//holds first names 
    String e_mail[] = new String [MAX];// holds emails
    String address[] = new String [MAX];//holds addresses 
    String phone[] = new String [MAX];// holds phone numbers 
    int total;//the counter that keeps track of our position

    // Create some GUI components
    JLabel lastnameLabel = new JLabel ("Last name", JLabel.LEFT);
    JTextField lastnameField = new JTextField (40);
    JLabel nameLabel = new JLabel ("First Name ", JLabel.LEFT);
    JTextField nameField = new JTextField (40);
    JLabel AddressLabel = new JLabel ("Address", JLabel.LEFT);
    JTextField AddressField = new JTextField (40);
    JLabel PhoneLabel = new JLabel ("Phone", JLabel.LEFT);
    JTextField PhoneField = new JTextField (40);
    JLabel EmailLabel = new JLabel ("Email", JLabel.LEFT);
    JTextField EmailField = new JTextField (40);
    JButton deleteButton = new JButton ("Delete");
    JButton saveButton = new JButton ("Save");
    JButton modifyButton = new JButton ("Update");
    JButton previousButton = new JButton ("<<");
    JButton searchButton = new JButton ("Search");
    JButton nextButton = new JButton (">>");
    JButton readButton = new JButton ("Read");
    JButton writeButton = new JButton ("Write");
    JButton clearButton = new JButton ("Clear");
    JLabel instructionsLabel = new JLabel ("Enter your name", JLabel.LEFT);
    JButton exitButton = new JButton ("Exit");


    // CONSTRUCTOR - Setup your GUI here
    public void HamzaTest () throws IOException
    {
        total = 0;
        //all fields to empty 
        for (int i = total ; i < names.length ; i++)
        {
            lastname [i] = "";
            names [i] = "";
            e_mail [i] = "";
            address [i] = "";
            phone [i] = "";
        }

        setTitle ("Hello World!"); // Create a window with a title
        setSize (640, 480); // set the window size

        // Create some Layouts
        GridLayout layout1 = new GridLayout (4, 1);
        GridLayout layout2 = new GridLayout (5, 1);

        // Set the frame and both panel layouts
        setLayout (layout1); // Setting layout for the whole frame
        pan1.setLayout (layout2); // Layout for Pan1
        pan2.setLayout (layout1); // Layout for Pan2

        saveButton.addActionListener (this); // Add an action listener to the buttons 
        deleteButton.addActionListener (this);
        modifyButton.addActionListener (this);
        previousButton.addActionListener (this);
        searchButton.addActionListener (this);
        nextButton.addActionListener (this);
        clearButton.addActionListener (this);
        exitButton.addActionListener (this);
        readButton.addActionListener (this);
        writeButton.addActionListener (this);


        // this allows the program to know if
        // the button was pressed

        // Add all the components to the panels
        pan1.add (lastnameLabel);
        pan1.add (lastnameField);
        pan1.add (nameLabel);
        pan1.add (nameField);
        pan1.add (AddressLabel);
        pan1.add (AddressField);
        pan1.add (PhoneLabel);
        pan1.add (PhoneField);
        pan1.add (EmailLabel);
        pan1.add (EmailField);
        //panel 2 is for buttons
        pan2.add (saveButton);
        pan2.add (deleteButton);
        pan2.add (modifyButton);
        pan2.add (previousButton);
        pan2.add (searchButton);
        pan2.add (nextButton);
        pan2.add (clearButton);
        pan2.add (readButton);
        pan2.add (writeButton);
        pan2.add (exitButton);
        pan2.add (instructionsLabel);

        // add the panels to the frame and display the window
        add (pan1);
        add (pan2);
        setVisible (true);//set the GUI window to visible
    }


    // ACTION LISTENER - This method runs when an event occurs
    // Code in here only runs when a user interacts with a component
    // that has an action listener attached to it
    public void actionPerformed (ActionEvent event)  /* throws IOException */
    {

        String command = event.getActionCommand (); // find out the name of the
        // component
        // that was used

        if (command.equals ("Save"))
        { // if the save button was pressed
            while (lastname [total] != "")//find the current position and save in the nearest 
                total++;
            System.out.println ("save button pressed"); // display message inconsole(for testing)
            System.out.println ("name:" + nameField.getText ()); // get the info located in the field component
            instructionsLabel.setText ("Thank you " + nameField.getText ()); // change the label message to 'thank you'
            //get the String values from the fields and set them to our arrays
            lastname [total] = lastnameField.getText ();
            names [total] = nameField.getText ();
            e_mail [total] = EmailField.getText ();
            address [total] = AddressField.getText ();
            phone [total] = PhoneField.getText ();
            //move to the next position
            total++;
            //sort the lists 
            Sort (lastname, names, e_mail, address, phone, total);
        }
        else if (command.equals ("Delete"))//if delete is pressed 
        {
            System.out.println ("delete button pressed");
            System.out.println (nameField.getText () + "was deleted");
            //set the current position to empty
            lastname [total] = ("");
            names [total] = ("");
            e_mail [total] = ("");
            address [total] = ("");
            phone [total] = ("");
            instructionsLabel.setText ("Deleted");
        }
        else if (command.equals ("Update"))//modify button was pressed 
        {
          //change a field without changing the current position meaning that it will overwrite what you already have 
            System.out.println (lastnameField.getText () + "was modified");
            lastname [total] = lastnameField.getText ();
            names [total] = nameField.getText ();
            e_mail [total] = EmailField.getText ();
            address [total] = AddressField.getText ();
            phone [total] = PhoneField.getText ();
            instructionsLabel.setText (lastnameField.getText () + " was modified");

        }
        else if (command.equals ("<<"))//previous button is pressed 
        {
            if (total > 0)//go back if it's not zero
                total--;
            System.out.println ("name: " + names [total]);
            //set the text field on the GUI to the current data
            lastnameField.setText (lastname [total]);
            nameField.setText (names [total]);
            EmailField.setText (e_mail [total]);
            AddressField.setText (address [total]);
            PhoneField.setText (phone [total]);
            instructionsLabel.setText (names [total]);
        }
        else if (command.equals ("Search"))//search for a specific name(last name)
        {
            int location = search (lastname, lastnameField.getText (), 0, 99);
            if (location >= 0)//if the name is found the mehtod will return a number larger than zero which is the location
            {
                lastnameField.setText (lastname [location]);
                nameField.setText (names [location]);
                EmailField.setText (e_mail [location]);
                PhoneField.setText (phone [location]);
                AddressField.setText (address [location]);
                instructionsLabel.setText ("found");
                System.out.println (lastname [location]);
                total = location;
            }
            else//the name wasn't found 
                instructionsLabel.setText ("not found");
        }
        else if (command.equals (">>"))//next button
        {
            if (total < 100)//move up if the position is smaller than a 100
                total++;
            System.out.println ("name" + names [total]);
            //set the text fields to the current data 
            lastnameField.setText (lastname [total]);
            nameField.setText (names [total]);
            EmailField.setText (e_mail [total]);
            AddressField.setText (address [total]);
            PhoneField.setText (phone [total]);
            instructionsLabel.setText (names [total]);
        }
        else if (command.equals ("Clear"))//clear the fields button
        {
            instructionsLabel.setText ("cleared");
            lastnameField.setText ("");
            nameField.setText ("");
            EmailField.setText ("");
            AddressField.setText ("");
            PhoneField.setText ("");
        }
        else if (command.equals ("Read"))//read file that already exists 
        {
            System.out.println ("At read");//reading
            Scanner input = null;
            try
            {
                input = new Scanner (readFile);//the file name was declared previously
                while (input.hasNext ())//if there are more lines to go
                {
                    lastname [total] = input.nextLine ();
                    names [total] = input.nextLine ();
                    e_mail [total] = input.nextLine ();
                    address [total] = input.nextLine ();
                    phone [total] = input.nextLine ();
                    total++;
                    System.out.println (total);
                }
                input.close ();//close the file stream
            }
            catch (FileNotFoundException e)//exception
            {
                System.out.println ("File not found");
            }
            //catch (IOException e)//exception
            {
                System.out.println ("Error writing to file");
            }
            //finally//makes sure the input stream is being closed
            {
                if (input != null)
                    input.close ();
            }
        }
        else if (command.equals ("Write"))//writes to text files to save the data 
        {
            System.out.println ("At write");
            PrintWriter output = null;
            try
            {
                output = new PrintWriter (writeFile);//the file name was declared previously 
                for (int i = 0 ; i < total ; ++i)//writes data to the file based on the current position
                {
                    output.println (lastname [i]);
                    output.println (names [i]);
                    output.println (e_mail [i]);
                    output.println (address [i]);
                    output.println (phone [i]);
                    output.println (""); //make a space in between people
                }
            }


            catch (IOException e)//exception
            {
                instructionsLabel.setText ("File cannot be read");
            }


            finally//makes sure the files is being closed so it would save
            {
                if (output != null)
                    output.close ();
            }


            instructionsLabel.setText ("Info has been saved to a file");
        }

        else if (command.equals ("Exit"))//exit the GUI
        {
            setVisible (false);//hide the GUI

        }

    }


    public static int Search (String lastnames[], String searchString, int min, int max)//search method
    {
        if (max < min)
            return -1;
        else
        {
            int mid = (max + min) / 2;
            if (searchString.compareToIgnoreCase (lastnames [mid]) < 0) //is below the midpoint
                return Search (lastnames, searchString, min, mid - 1);
            else if (searchString.compareToIgnoreCase (lastnames [mid]) > 0) //is above the midpoint
                return Search (lastnames, searchString, mid + 1, max);
            else
                return mid;     //of the searched item has been found
        }
    }


    public static int search (String[] names, String name, int min, int max)//temporary search method
    {

        for (int i = 0 ; i < MAX ; i++)
        {
            if (names [i].compareTo (name) == 0)
                return i;
        }
        return -1;
    }


    public static void Sort (String lastname[], String names[], String e_mail[], String address[], String phone[], int total)//insertion sort
    {
        String tempLS; //temporary variable for last names
        String tempN; //temporary variable for first names
        String tempA; //temporary variable for addresses
        String tempP; //temporary variable for phones
        String tempE; //temporary variable for emails
        int j;
        for (int i = 1 ; i < total ; i++) // going through list --> start i at 1
            // to make one less comparison
            {
                tempLS = lastname [i]; // setting temp at start of loop
                tempN = names [i];
                tempA = address [i];
                tempP = phone [i];
                tempE = e_mail [i];

                j = i - 1; // to check names before
                while (j >= 0 && tempLS.compareToIgnoreCase (lastname [j]) < 0) // checks to see if
                    // previous names
                    // are greater ->
                    // then makes swap
                    {
                        lastname [j + 1] = lastname [j]; // if previous name is greater, moves
                        // greater value up the array by 1
                        names [j + 1] = names [j];
                        e_mail [j + 1] = e_mail [j];
                        address [j + 1] = address [j];
                        phone [j + 1] = phone [j];
                        j--; // compares to previous numbers
                    }
                lastname [j + 1] = tempLS; // swap //+1 to make up for j=-1
                names [j + 1] = tempN;
                e_mail [j + 1] = tempE;
                address [j + 1] = tempA;
                phone [j + 1] = tempP;
            }
    }


    // Main method
    public static void main (String[] args) throws IOException
    {
        AddressbookFinal frame1 = new AddressbookFinal (); // Start the GUI

    }
}

Answer 1

你有两个选择，要么改变

// CONSTRUCTOR - Setup your GUI here
public void HamzaTest() throws IOException {

成为类的正确构造函数，

public AddressbookFinal() throws IOException {

或者您从 main 方法调用 HamzaTest 方法

// Main method
public static void main(String[] args) throws IOException {
    EventQueue.invokeLater(new Runnable() {
        @Override
        public void run() {
            try {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                AddressbookFinal frame1 = new AddressbookFinal(); // Start the GUI
                frame1.HamzaTest();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    });
}

您应该看看Providing Constructors for Your Classes了解更多详情。

对于 EventQueue.invokeLater 的原因，您应该查看 Concurrency in Swing