Input/Output - Beginning Java 8 Language Features - page 341

Listing 7-33. A Custom Java I/O Reader Class Named LowerCaseReader
// LowerCaseReader.java
package com.jdojo.io;
import java.io.Reader;
import java.io.FilterReader;
import java.io.IOException;
public class LowerCaseReader extends FilterReader{
public LowerCaseReader(Reader in) {
super(in);
}
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
int count = super.read(cbuf, off, len);
if (count != -1) {
// Convert all read characters to lowercase
int limit = off + count;
for (int i = off; i < limit; i++) {
cbuf[i] = Character.toLowerCase(cbuf[i]);
}
}
return count;
}
}
Listing 7-34 shows how to use your new class. It reads from the file luci4.txt . It reads the file twice: the first
time by using a LowerCaseReader object and the second time by wrapping a LowerCaseReader object inside a
BufferedReader object. Note that while reading the licu4.txt file the second time, you are taking advantage of the
readLine() method of the BufferedReader class. The test class throws an exception in the declaration of its main()
method to keep the code readable. The luci4.txt file should exist in your current working directory. Otherwise, you
will get an error when you run the test program.
Listing 7-34. Testing the Custom Reader Class, LowerCaseReader
// LowerCaseReaderTest.java
package com.jdojo.io;
import java.io.FileReader;
import java.io.BufferedReader;
public class LowerCaseReaderTest {
public static void main(String[] args) throws Exception {
String fileName = "luci4.txt";
LowerCaseReader lcr = new LowerCaseReader(new FileReader(fileName));
System.out.println("Reading luci4.txt using LowerCaseReader:");
int c = -1;
while ((c = lcr.read()) != -1) {
System.out.print((char) c);