Why am I receiving a .class is expected? Trying to call a method in java

Question

I'm pretty new to programming feel free to be harsh in your replies. Anything helps. Basically I'm trying to call in a method LineCount() but when I try to compile the command prompt complains about .class being expected at String[A] (line 8 I believe)

*Thank you guys for all your help! My code works now! I really appreciate all the input

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

public class FileCount{

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

        String[] in = new Scanner(new File(args[0]));
        System.out.println(lineCount(String[] in);

    }

    public static void lineCount(String[] A){

        // check number of command line arguments
        if(args.length != 1){
            System.err.println("Usage: LineCount file");
            System.exit(1);
        }

        // count lines, words, and chars in file
        int lineCount = 0;
        while( in.hasNextLine() ){
            in.nextLine();
            lineCount++;
        }
        in.close();

        System.out.println( args[0]+" contains "+lineCount+" lines" );

    }

}

You don't need to redeclare the type of `in` when you pass it as an argument in your `lineCount` invocation. — Sotirios Delimanolis, Jul 10 '14 at 04:50

score 4 · Answer 1 · answered Jul 10 '14 at 04:51

4

First of all

  System.out.println(lineCount(String[] in); // this is incomplete need to close)

Assuming you did mistake while you putting the question here, Change

 System.out.println(lineCount(String[] in));

To

  System.out.println(lineCount(in));

answered Jul 10 '14 at 04:51

Ruchira Gayan Ranaweera

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Mustafa sabir · Accepted Answer · 2014-07-10T05:24:17.707

-> There are many mistakes in your code, Besides other answers want to add that, Since you are passing lineCount(in) as an argument to the linecount() method , then refer to the parameter in lineCount(String[] A) now via A variable and not in.

-> Also you cannot refer to args inside linecount() method since it is a parameter of main() method and hence is limited to it in its scope.

-> You cannot do this String[] in = new Scanner(new File(args[0])); , you are assigning a Scanner instance to an String Array, you have to do it like this

Scanner in = new Scanner(new File(args[0]));

-> You are calling linecount() inside a System.out.println() method , although your method linecount() has a return type of void, Dont put your method inside print() function , because anyways it has got print() statements inside it.

-> Maybe last , there could be more , Since your in variable is of type Scanner , change your method declaration to

 public static void lineCount(Scanner in){

and now call it like lineCount(in) from main().

Edit :- Since you are a beginner i will give you working code for your question:-

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

public class FileCount{

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


      // check number of command line arguments, and check it in main()
       if(args.length != 1){
            System.err.println("Usage: LineCount file");
            System.exit(1);
        }

    Scanner in = new Scanner(new File(args[0]));
    System.out.println( args[0]+" contains "+lineCount(in)+" lines" ); //call this line in main() and not in linecount() as you refer to both args and need the linecount.

    }

    public static int lineCount(Scanner in){


        // count lines, words, and chars in file
        int lineCount = 0;
        while( in.hasNextLine() ){
            in.nextLine();
            lineCount++;
        }
        in.close();

        return lineCount; //return the linecount from method 

    }

}

This answer covers most mistakes, code has a lot of mistakes in it. — Abhijeet Panwar, Jul 10 '14 at 05:22

score 1 · Answer 3 · answered Jul 10 '14 at 05:25

Your first problem String[] in = new Scanner(new File(args[0])); creating a Scanner object and asigning it to an array it does not work like this. Change your code to read the file and store it in some arraylist like

    List<String> list= new ArrayList<String>();
    Scanner in = new Scanner(new File(args[0]));

    while (in.hasNextLine()) {
        // find next line
        String line = in.nextLine();
        list.add(line);
    }

Then if you want can convert to list to String array which is not really necessary like this

    String[] strArr = list.toArray(new String[0]);

            System.out.println(java.util.Arrays.toString(strArr));
    lineCount(strArr);

Then call the lineCount() method which counts the lines in the files.

public static void lineCount(String[] A){
    System.out.println("File contains "+A.length+" lines" );

}

Why am I receiving a .class is expected? Trying to call a method in java

3 Answers3