Java LineNumberReader Example
November 18, 2023
java.io.LineNumberReader implements BufferedReader class. LineNumberReader keeps tracks of line number. It means while reading data, it can also provide the line number. By default, LineNumberReader denotes first line as 0. We can specify a number using setLineNumber(int). It does not mean that LineNumberReader will start reading from specified line, it only displays incremental line number.
Example
LineNumberReaderDemo.java
package com.cp.io;
import java.io.FileReader;
import java.io.IOException;
import java.io.LineNumberReader;
public class LineNumberReaderDemo {
public static void main(String[] args) throws IOException {
FileReader fr = null;
LineNumberReader lineNumReder = null;
try{
System.out.println("Before changing line number\n");
fr = new FileReader("D:/cp/text.txt");
lineNumReder = new LineNumberReader(fr);
String str;
while((str=lineNumReder.readLine())!= null){
System.out.print(lineNumReder.getLineNumber()+":");
System.out.println(str);
}
System.out.println("\nAfter changing line number\n");
fr = new FileReader("D:/cp/text.txt");
//set line number as you want
lineNumReder = new LineNumberReader(fr);
lineNumReder.setLineNumber(10);
while((str=lineNumReder.readLine())!= null){
System.out.print(lineNumReder.getLineNumber()+":");
System.out.println(str);
}
}catch(Exception e){
e.printStackTrace();
}finally{
fr.close();
lineNumReder.close();
}
}
}
Before changing line number 1:Hello World! 2:This is LineNumberReader Program. 3:Happy Learning. After changing line number 11:Hello World! 12:This is LineNumberReader Program. 13:Happy Learning.
