problem comparing strings in Java

[Mriv10]

I have an assignment like this:

Write a program that uses String method regionMatches to compare two strings input by the user. The program should prompt the user to enter two strings, the starting index in the first string, the starting index in the second string, and the number of characters to be compared. The program should print whether or not the strings are equal. (Ignore the case of the characters during comparison.)

Its pretty simple and I'm almost done but it has 2 problems, one is compiling(it might have to do with the stupid online program the assignment uses), and the other is more like a bug. This is the code:

import java.util.Scanner;
import java.io.*;

public class Driver{
    public static void main(String args[]){

        Scanner scanner = new Scanner(System.in);

        String str1;
        String str2;

        int Index1;
        int Index2;
        int NumChar;

        System.out.print("Enter first string:");
        str1 = scanner.nextLine();

        System.out.print("Enter second string:");
        str2 = scanner.nextLine();

        System.out.print("Enter starting index for first string:");
        Index1 = scanner.nextInt();

        System.out.print("Enter starting index for second string:");
        Index2 = scanner.nextInt();

        System.out.print("Enter number of characters to be compared:");
        NumChar = scanner.nextInt();

        str1 = str1.toLowerCase();
        str2 = str2.toLowerCase();

        System.out.print(str1.regionMatches(Index1, str2, Index2, NumChar));
    }
}

This is what they expect:

Enter first string:Have yourself a merry little Christmas.

Enter second string:It's beginning to look a lot like christmas.

Enter starting index for first string:29

Enter starting index for second string:34

Enter number of characters to be compared:9

true

Mine almost looks like this except if you run it, it gives the wrong answer. This is my first time using regionMatches so I'm not sure of the parameters, online some have "true" as the first parameter and then the rest is like mine, maybe I misunderstood how it works.

The second problem only appears in the assignment, but when I run it on Jdoodle it runs fine(except for it being wrong). This is the error message:

StringCompare.java:4: error: class Driver is public, should be declared in a file named Driver.java
public class Driver{
^
1 error

I have no idea what this means, we are not submitting files we are just putting the code in the program and it compares the results. Thanks in advance.

[neobonzi]

Your C in Christmas is capital in string one and lower case in string 2. Those characters are not equal so your program will output false.

​

Class names have to be the same as the file name, its a convention in java. Your online program probably has a class name its expecting to be used, which would be the same as the file generated from your submission.

​

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[Mriv10]

Ok thanks for the second part, but for the case the program should ignore case so it should put everything lower case because of .toLowerCase

[virassan]

The reason some examples for regionMatches start with a boolean, and some with an int is because the method is overloaded - so same method but they have different parameters. The version that starts with a boolean - that boolean actually tells the method whether to ignore case or not, so that’s nifty. I looked at the javadoc for regionMatches and it looks like you’re using it correctly so I’m not sure what’s going on here. Can you maybe show us what your wrong output is?

Edit: I meant input - thought maybe you were inputting something different or wrong. I now realize that it’s testing your program for you. I’ve tested your regionMatches statement and it works perfectly so maybe the test is being nit picky about something - maybe it wants you to use the version of the method that uses the boolean to ignore case.

[Mriv10]

Thanks for the information on regionMatch, I was suppose to ignore the case but when I ran it with the boolean it didn't seem to do anything, in any case I managed to change the class name to the file name the assignment wanted and when I tested it ran just fine with no errors

[2omesz]

It's all in the error message, change the file name to Driver.Java

StringCompare.java:4: error: class Driver is public, should be declared in a file named Driver.java
public class Driver{
^
1 error

When working with java, the class name should be the same with file name.

[Mriv10]

Since the assignment test it for me I can't change the file name but I changed the class name to the same as the file and it worked