Replace character in a string

package ch4_package;
import java.io.*;
//import java.util.Vector;
public class Test_This {
Test_This tt = new Test_This();
public static void main(String[] args) throws IOException
{
// TODO Auto-generated method stub
InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(isr);
String str ="";
try{
//System.out.println("---While Loop---");
System.out.print("Please enter a word: ");
str = br.readLine();
Process pp = new Process();
pp.read_input(str);
}//try
catch(NumberFormatException e) { System.out.println("data was blank");}
}
}
class Process
{
public void read_input(String str)
{
System.out.println("list of character in:\t " + str);
String str_replace = str.replace(' ', '/');
System.out.println("Replace character in :\t " + str_replace);


}
}//end of class process