Buffered Reader read certain line and text

Question

This is my first post, so i'm not sure how things work here. Basically, i need some help/advice with my code. The method need to read a certain line and print out the text after the inputted text and =

The text file would like

A = Ant

B = Bird

C = Cat

So if the user it input "A" it should print out something like

-Ant

So far, i manage to make it ignore "=" but still print out the whole file

here is my code:

public static void readFromFile() {
    System.out.println("Type in your word");
    Scanner scanner = new Scanner(System.in);
    String input = scanner.next();
    String output = "";
    try {
        FileReader fr = new FileReader("dictionary.txt");           
        BufferedReader br = new BufferedReader(fr);            
        String[] fields;
        String temp;
        while((input = br.readLine()) != null) {
            temp = input.trim();
            if (temp.startsWith(input)) {
                String[] splitted = temp.split("=");
                output += splitted[1] + "\n";
            }
        }
        System.out.print("-"+output);
    }
    catch(IOException e) {

    }
}

Answer 1

It looks like this line is the problem, as it will always be true.

if (temp.startsWith(input))

You need to have a different variables for the lines being read out of the file and for the input you're holding from the user. Try something like:

String fileLine;
while((fileLine = br.readLine()) != null)
    {
        temp = fileLine.trim();
        if (temp.startsWith(input))
        {
            String[] splitted = temp.split("=");
            output += splitted[1] + "\n";
        }
    }

Answer 2

try this, it works: STEPS:

1) read input using scanner 2) read file using bufferedreader 3) split each line using "-" as a delimiter 4) compare first character of line with input 5) if first character is equal to input then print the associated value , preceded by a "-"

import java.io.BufferedReader; 
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.File;
import java.util.Scanner; 
class myRead{
    public static void main(String[] args) throws FileNotFoundException, IOException {
        System.out.println("Type in your word");
        Scanner scanner = new Scanner(System.in);
        String input = scanner.next();
        long numberOfLines = 0;
        BufferedReader myReader = new BufferedReader(new FileReader("test.txt")); 
        String line = myReader.readLine();
            while(line != null){
                String[] parts = line.split("=");
                if (parts[0].trim().equals(input.trim())) {
                System.out.println("-"+parts[1]);
                }
                line = myReader.readLine();
            } 
}
}

OUTPUT (DEPENDING ON INPUT):

- Ant
- Bird
- Cat

Answer 3

You can use useDelimiter() method of Scanner to split input text

scanner.useDelimiter("(.)*="); // Matches 0 or more characters followed by '=', and then gives you what is after `=`

The following code is something I've tried in IDEONE ( http://ideone.com/TBwCFj )

Scanner s = new Scanner(System.in);
        s.useDelimiter("(.)*=");
        while(s.hasNext())
        {
            String ss = s.next();
            System.out.print(ss);

        }
 /**
  * Output
  *
  */
  Ant
  Bat

Answer 4

You need to first split the text file by new line "\\n" (assuming after each "A = Ant", "B = Bird" ,"C = Cat" declaration it starts with a new line) and THEN locate the inputted character and further split that by "=" as you were doing.

So you will need two arrays of Strings (String[ ]) one for each line and one for the separation of each line into eg "A" and "Ant". You are very close.