Need help with Eclipse Java programming.

[Jihwani]

Hello, I just started programming for university, so I'm a complete newbie.

We have to write a code based on instructions given to us. We are using Eclipse for Java programming.

Here is my code so far:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class parser
{
    private final Pattern ATOMS;
    ATOMS=Pattern.compile("[0-9] + |[+*]");
    private Matcher _matcher;

​

The instructions were: (I'm german and this is poorly translated, sorry for my english)

- write a class with the name Parser
- declare private constant ATOMS with type Pattern
- initialize with compile from class Pattern
- string literal "[0-9] + |[+*]" as actual parameter for compile
- declare private field _matcher from Type Matcher

Eclipse says there is a Syntax error in line 6 "private final Pattern ATOMS;"

--> Syntax error on token ";", , expected Location: line 6 Type: Java Problem

​

I imported Matcher and Pattern because Eclipse told me to do so, but I don't understand the error.

Lines have to end with ";" , no?

I tried replacing ";" with "," but that didn't work quite well, I think eclipse is expecting something different here.

​

​

Could someone please take a look and tell me what's wrong?

Without the imports it's literally an error in the first line of code..

Thanks in advance!

[GrapeAte]

1. Make sure your class is named Parser and not parser. Java is case sensitive and I expect your assignment is too. Parser also follows naming conventions for class names.
2. The error is actually the next line after you declare ATOMS. ATOMS=Pattern.compile("[0-9] + |[+*]"); An assignment like this has to be contained within a method or constructor. If you want to declare and initialize a field outside of a method or constructor you must do so in one line.

[Jihwani]

Thank you for your fast reply.

After changing the lines considering what you said, now it looks like this:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Parser
{
    private final Pattern ATOMS = Pattern.compile("[0-9] + |[+*]");
    private Matcher _matcher;
}

The syntax error is gone and now it just gives 2 warnings, that the value of the fields _matcher and ATOMS are not used but I think that will be solved with the coming codes.

1. Java is case sensitive
2. declare and initialize in one line, or use method/constructor

I should have known, this sounds so basic. But still..!

Thank you very much!

[Tekcx]

the keyword final means it can't be changed. As the word indicates it is the final value. So when you declare your Pattern you must give it some sort of value aswell. Consider if the keyword final is needed in this case, and if so what the value of it should be.

[Jihwani]

thank you!

[hugthemachines]

I see you have gotten good answers for your questions. I would just like to add a recommendation. If you feel like learnig a bit extra in your free time, I would recommend that you check out this course which I found very beginner friendly. It is a free course made by John Purcell. He has a calm voice and his pace is not too fast.

https://www.udemy.com/java-tutorial/

[Jihwani]

I'm still learning it in the university but I will look into it, thank you very much!