System.out.println(
        String.class.getName()+ ".class");
    System.out.println(
        String.class.getName().
        replaceAll(".","/") + ".class");

java.lang.String.class

java/lang/String/class

////////////////.class

    System.out.println(
        String.class.getName().
        replaceAll("\\.","/") + ".class");  

    System.out.println(
        String.class.getName().
        replaceAll("\\Q.\\E","/") + ".class");  

    System.out.println(
        String.class.getName().
        replaceAll(Pattern.quote("."),"/") + ".class");  

/**
 * Returns a literal pattern <code>String</code> for the specified
 * <code>String</code>.
 *
 * <p>This method produces a <code>String</code> that can be used to
 * create a <code>Pattern</code> that would match the string
 * <code>s</code> as if it were a literal pattern.</p> Metacharacters
 * or escape sequences in the input sequence will be given no special
 * meaning.
 *
 * @param s The string to be literalized
 * @return A literal string replacement
 * @since 1.5
 */
 public static String quote(String s) {
 int slashEIndex = s.indexOf("\\E");
 if (slashEIndex == -1)
 return "\\Q" + s + "\\E";
 StringBuilder sb = new StringBuilder(s.length() * 2);
 sb.append("\\Q");
 slashEIndex = 0;
 int current = 0;
 while ((slashEIndex = s.indexOf("\\E", current)) != -1) {
 sb.append(s.substring(current, slashEIndex));
 current = slashEIndex + 2;
 sb.append("\\E\\\\E\\Q");
 }
 sb.append(s.substring(current, s.length()));
 sb.append("\\E");
 return sb.toString();
 }

import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
public class CheckSpecialCharacterString {
 
 /**
 * Check whether the each character of String is special character or not using java
 * @author www.instanceofjava.com
 */
 
public static void main(String[] args) {
String Str="Java String interview questions*$%";
 
String specialCharacters=" !#$%&'()*+,-./:;<=>?@[]^_`{|}";
 
for (int i = 0; i < Str.length(); i++) {
 
 if (specialCharacters.contains(Character.toString(Str.charAt(i))))
 {
 
 System.out.println(Str.charAt(i)+": is a special character");
 } 
 }
 
}
 
}