java - 异常处理错误

Question

我正在开发一个基于2个类的程序，这些类可以转换军事时间，同时还使用异常处理。我遇到3个编译器错误。前两个在Time类中，它表示找不到可变时间的符号。第三个错误与我试图在TimeConverterTest类中显示结果的方式有关，它说它找不到MilitaryTime变量。

import javax.swing.*;

public class Time
{

    private int hours;
    private int minutes;
    private boolean afternoon;
    String  am_pm;

    public Time(String time)
    {

    }

    public String convertToMilitary(String militaryTime)
    {
      try{
            if (time == null)
            {
                throw new IllegalArgumentException ("No time was entered");

            }
            else if (time > 5)
            {
                throw new IllegalArgumentException ("Less than 5 characters were entered");
            }
            else
            {
                 if ( militaryTime.charAt(2) != ':' )
                {
                    throw new IllegalArgumentException ("The third character was not a colon");
                 }
                 else if ( !Character.isDigit( militaryTime.charAt( 0 ) ) )
                {
                     throw new IllegalArgumentException ("The first character was not passed as a digit");
                 }
                else if ( !Character.isDigit( militaryTime.charAt( 1 ) ) )
                {
                     throw new IllegalArgumentException ("The second character was not passed as a digit");
                 }
                else if ( !Character.isDigit( militaryTime.charAt( 2 ) )  )
                {
                     throw new IllegalArgumentException ("The fourth character was not passed as a digit");
                 }
                else if ( !Character.isDigit( militaryTime.charAt( 4 ) ) )
                {
                     throw new IllegalArgumentException ("The fifth character was not passed as a digit");
                 }
                else
                {

                    hours = Integer.parseInt(militaryTime.substring( 0,2 ));
                    minutes = Integer.parseInt( militaryTime.substring( 3,5 ));

                     if( hours > 23)
                    {
                        throw new IllegalArgumentException ("Hours passed were greater than 23");
                     }
                    else if( minutes > 59)
                    {
                        throw new IllegalArgumentException ("Minutes passed were greater than 59");
                     }
                     else if (hours > 12)
                    {
                        afternoon = false;
                    }
                     else if (hours == 0)
                    {
                        hours = 12;

                    }
                     else if (hours == 12)
                    {
                        afternoon = true;

                    }
                     else
                    {
                        System.out.println(hours + ":" + minutes );
                    }

                        }

                   }    
        }
       catch (IllegalArgumentException exception)
        {
            JOptionPane.showMessageDialog(null,
                    exception.getMessage(),
                    "Invalid Argument", JOptionPane.ERROR_MESSAGE);
            System.exit(0);
        }

      String  am_pm = hours + ":" + minutes;

        return "\n\n" + hours + ":" + minutes + " " + am_pm + "\n\n";
    }

}

并且TimeConverterTest是

import javax.swing.*;
import java.util.*;
import java.util.ArrayList;
import java.util.regex.Pattern;

public class TimeConverterTest {

    public static final String[] menuChoice = {"Convert Military Time to Standard",
            "Convert Standard Time to Military",
            "Exit the System"};

    public static void main( String[] args )
    {
        while(true){
            JFrame frame = new JFrame("TIME CONVERSION MACHINE");
            String option = (String) JOptionPane.showInputDialog(frame,
                    "What do you want to do?",
                    "Time Conversion Machine",
                    JOptionPane.QUESTION_MESSAGE,
                    null,
                    menuChoice,
                    menuChoice[0]);

            int choice = Arrays.asList(menuChoice).indexOf(option) + 1;

            System.out.print(choice);


            Scanner input;

            switch (choice) {
                case 1:


                    input = new Scanner(System.in);

                    // Prompt user to enter Military time with message "Please enter Military Time:"
                    //CODE to make it work

                    System.out.printf("Please enter Military Time: ");

                    // Create militaryTime variable to accept input
                    //CODE to make it work;

                    String time;
                    time = input.nextLine();
                    // Create new 'timeToConvert' object using militaryTime
                    //CODE to make it work

                    Time timeToConvert = new Time( time);  


                    // Using your newly created object call the necessary method to convert the time and
                    // Display your results


                    //Display your results
                    String results =  timeToConvert.convertToMilitary(militaryTime);
                    JOptionPane.showMessageDialog(null,results);

                    break;

                case 2:


                case 3:

                    System.exit(0);

            }

        }
    }

}// end of class TimeConverterTest

Answer 1

如果未声明变量，则将出现cannot be resolved to a variable编译错误

在Time类中

public String convertToMilitary(String militaryTime) {
    try {
        if (militaryTime == null) {
            throw new IllegalArgumentException("No time was entered");

        } else if (militaryTime.length() < 5) {
            throw new IllegalArgumentException("Less than 5 characters were entered");

TimeConverterClass

        String results = timeToConvert.convertToMilitary(time);