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Java Interpreter: Parsar Program  RSS feed

 
Justin Liao
Greenhorn
Posts: 2
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For the parser class, I need to use parseProgram() to take a filename as a parameter, opens and read the contents of the file, and returns an ArrayList of Statement objects.
Since I am new to Java, I do not know where to start from.
I also like to know is the ParseLine method so far is right.

Thanks,

import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;

public class Parser
{

//Here is I struggle, I have no idea how to use parseProgram to store into an array list
public static ArrayList<Statement> parseProgram(String filename)
throws IOException
{

}

// parseLine() takes a line from the input file and returns a Statement
// object of the appropriate type. This will be a handy method to call
// within your parseProgram() method.
private static Statement parseLine(String line)
{
// Scanners can be used to break Strings into pieces, too!
Scanner scanner = new Scanner(line);
// The next() method returns the next word out of the String.
// use the first word to decide on a statement type.
String statementType = scanner.next();

Statement statement = null;
29.

if (statementType.equals("LET"))
{
char variable = scanner.next().charAt(0);
int value = scanner.nextInt();

statement = new LetStatement(variable, value);
}

return statement;
}
}
 
Rob Spoor
Sheriff
Posts: 21135
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Welcome to the Ranch!

Will you please UseCodeTags next time? Also, please add some indentations when using code tags. I would have added the code tags for you but without indentation it won't make much sense.
 
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