Why is BufferedReader not reading, but clearing my text file?

[peter pham]

Followed this: http://www.mkyong.com/java/how-to-read-file-from-java-bufferedreader-example/

public static final String FILENAME="BinarySearchTree.txt";
....
public BinarySearchTree(TNode r) throws IOException {
		root = r;
		textfile = new File(FILENAME);
		fw = new FileWriter(textfile.getAbsoluteFile());
		bw = new BufferedWriter(fw);
		br = new BufferedReader(new FileReader(FILENAME));
	}

public void createFromFile() throws IOException {
		String currLine;
		
		// read a line.  while there is one...
		while((currLine = br.readLine()) != null) {
			
			StringTokenizer st = new StringTokenizer(currLine, DELIMITER);
			
			while(st.hasMoreTokens()) {
				String currValue = st.nextToken();
				TNode newNode = new TNode(currValue);
				if(root == null) {
					root = newNode;
				}
				else {
					insert(root, newNode);
				}
			}
		}
		br.close();
	}

In the constructor I create the BufferedReader using the FileReader and path to the input text file(in same dir as this project). When I am done reading I close it. In the debugger it is unable to read a single line, then goes to close the file.

[Paul Clapham]

It's the BufferedWriter which is clearing your file, not the reader.

[peter pham]

Paul Clapham wrote:It's the BufferedWriter which is clearing your file, not the reader.

Thanks that was it.

[Daniel Baker]

Since Java 7, you can use the try-with-resources statement around the BufferedReader so you don't have to close it explicitly.

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class ReadFile_BufferedFileReader_ReadLine {
	public static void main(String [] args) throws IOException {
		String fileName = "c:\\temp\\2.sample-10KB.txt";
		FileReader fileReader = new FileReader(fileName);
		
		try (BufferedReader bufferedReader = new BufferedReader(fileReader)) {
			String line;
			while((line = bufferedReader.readLine()) != null) {
				System.out.println(line);
			}
		}
	}
}

Source: https://funnelgarden.com/java_read_file/