Explore Westonci.ca, the premier Q&A site that helps you find precise answers to your questions, no matter the topic. Explore comprehensive solutions to your questions from a wide range of professionals on our user-friendly platform. Explore comprehensive solutions to your questions from knowledgeable professionals across various fields on our platform.

- JAVA - Okay I have been attempting this for the past hour and I am really stuck and keep getting an error... The error says that I keep missing a main thread but its there... help!
Given a main program that searches for the ID or the name of a student from a text file, complete the findID() and the findName() methods that return the corresponding information of a student. Then, insert a try/catch statement in main() to catch any exceptions thrown by findID() or findName(), and output the exception message. Each line in the text file contains the name and the ID of a student, separated by a space.
Method findID() takes two parameters, a student's name and a Scanner object containing the text file's contents. Method findID() returns the ID associated with the student's name if the name is in the file, otherwise the method throws an Exception object with the message "Student ID not found for studentName", where studentName is the name of the student.
Method findName() takes two parameters, a student's ID and a Scanner object containing the text file's contents. Method findName() returns the name associated with the student's ID if the ID is in the file, otherwise the method throws an Exception object with the message "Student name not found for studentID", where studentID is the ID of the student.
The main program takes three inputs from a user: the name of a text file (String), a user choice of finding the ID or the name of a student (int), and the ID or the name of a student (String). If the user choice is 0, findID() is invoked with the student's name as one of the arguments. If the user choice is 1, findName() is invoked with the student's ID as one of the arguments. The main program finally outputs the result of the search or a message if an exception is caught.
Ex: If the input of the program is:
roster.txt 0 Reagan
and the contents of roster.txt are:

Reagan rebradshaw835
Ryley rbarber894
Peyton pstott885
Tyrese tmayo945
Caius ccharlton329
the output of the program is:

rebradshaw835
Ex: If the input of the program is:

roster.txt 0 Mcauley
the program outputs an exception message:

Student ID not found for Mcauley
Ex: If the input of the program is:

roster.txt 1 rebradshaw835
the output of the program is:

Reagan
Ex: If the input of the program is:

roster.txt 1 mpreston272
the program outputs an exception message:

Student name not found for mpreston272
import java.util.Scanner;
import java.io.FileInputStream;
import java.io.IOException;

public class LabProgram {

public static String findID(String studentName, Scanner infoScnr) throws Exception {

/* Type your code here. */

}

public static String findName(String studentID, Scanner infoScnr) throws Exception {

/* Type your code here. */

}

public static void main(String[] args) throws IOException {
Scanner scnr = new Scanner(System.in);
String studentName;
String studentID;
String studentInfoFileName;
FileInputStream studentInfoStream = null;
Scanner studentInfoScanner = null;

// Read the text file name from user
studentInfoFileName = scnr.next();

// Open the text file
studentInfoStream = new FileInputStream(studentInfoFileName);
studentInfoScanner = new Scanner(studentInfoStream);

// Read search option from user. 0: findID(), 1: findName()
int userChoice = scnr.nextInt();

// FIXME: findID() and findName() may throw an Exception.
// Insert a try/catch statement to catch the exception and output the exception message.

if (userChoice == 0) {
studentName = scnr.next();
studentID = findID(studentName, studentInfoScanner);
System.out.println(studentID);
}
else {
studentID = scnr.next();
studentName = findName(studentID, studentInfoScanner);
System.out.println(studentName);
}

studentInfoStream.close();
}
}


Sagot :

tonb

Answer:

import java.util.Scanner;

import java.io.FileInputStream;

import java.io.IOException;

public class LabProgram {

 public static String findID(String studentName, Scanner infoScnr) throws Exception {

   while (infoScnr.hasNextLine()) {

     String[] parts = infoScnr.nextLine().split(" ");

     if (parts[0].trim().equals(studentName)) {

       return parts[1].trim();

     }

   }

   throw new Exception("Student ID not found for " + studentName);

 }

 public static String findName(String studentID, Scanner infoScnr) throws Exception {

   while (infoScnr.hasNextLine()) {

     String[] parts = infoScnr.nextLine().split(" ");

     if (parts[1].trim().equals(studentID)) {

       return parts[0].trim();

     }

   }

   throw new Exception("Student ID not found for " + studentID);

 }

 public static void main(String[] args) throws IOException {

   Scanner scnr = new Scanner(System.in);

   String studentName;

   String studentID;

   String studentInfoFileName;

   FileInputStream studentInfoStream = null;

   Scanner studentInfoScanner = null;

   // Read the text file name from user

   studentInfoFileName = scnr.next();

   // Open the text file

   studentInfoStream = new FileInputStream(studentInfoFileName);

   studentInfoScanner = new Scanner(studentInfoStream);

   // Read search option from user. 0: findID(), 1: findName()

   int userChoice = scnr.nextInt();

   try {

     if (userChoice == 0) {

       studentName = scnr.next();

       studentID = findID(studentName, studentInfoScanner);

       System.out.println(studentID);

     } else {

       studentID = scnr.next();

       studentName = findName(studentID, studentInfoScanner);

       System.out.println(studentName);

     }

   } catch (Exception ex) {

     System.out.println(ex.getMessage());

   }

   scnr.close();

   studentInfoStream.close();

 }

}

Explanation:

- You should call your file the same as your class (i.e., LabProgram.java)

- I added a try/catch to both find calls, to catch the exception

- The find methods are very similar, they loop through the lines of the roster, splitting each line at a space and doing string comparison.

Your visit means a lot to us. Don't hesitate to return for more reliable answers to any questions you may have. Thanks for using our service. We're always here to provide accurate and up-to-date answers to all your queries. Keep exploring Westonci.ca for more insightful answers to your questions. We're here to help.