Java I/O Lab Java I/O Lab In this lab, you will learn some of the common I/O operations in Java. The Java I/O API libraries will be necessary to complete this lab: http://java.sun.com/j2se/1.4.2/docs/api/java/io/package-summary.html UNIX "ls" Utility in Java Write a class called ls whose main(String[] args) method prints to standard out the files/directories contained in the current directory if no args[0] specified, or, the directory mentioned in args[0]. Don't worry about formatting the output; just print one file or directory name per output line. The class will look like:
public class ls {
public static void main(String[] args) throws IOException {
...
}
}
You will need the javadoc for File. Write a for-loop that walks the array of file names returned to you from File.list(). UNIX "cat" Utility in Java Write a class called cat whose main(String[] args) method reads all the text from the file mentioned on the command-line (args[0]) line-by-line and prints it to standard out. Open a FileReader and then wrap it with a BufferedReader so you can use method readLine() to get a line of input. Note that readLine() strips the '\n' character off the end of the line so use System.out.println() to spit the lines out.
public class cat {
public static void main(String[] args) throws IOException {
if ( args.length==0 ) {
return;
}
String fileName = args[0];
...
}
}
UNIX "cp" Utility in Java If you have time... Write a class called cp whose main(String[] args) method copies one file (could be binary!) to another (args[0] to args[1]). You should read the files byte-by-byte so use FileInputStream and FileOutputStream. Use read() to get a single char and use write(char) to write the character. Don't forget to close the files properly using the finally clause.
public class cp {
public static void main(String[] args) throws IOException {
if ( args.length!=2 ) {
return;
}
String fromFileName = args[0];
String toFileName = args[1];
...
}
}
