Trim the String without trim()

class StringDemo4
{
static String Reverse(String s)
{
int n = s.length();
String c = "";
int i;
for(i=n;i>0;i--)
{
c += s.charAt(i-1);
}
return c;
}
public static void main(String... s)
{
System.out.println(Reverse("i am an indian"));
}
}
class StringDemo6
{
static String LTrim(String s)
{
String c = "";
int i=0;
while( s.charAt(i) == ' ' )
{
i++;
}
while(i<s.length())
{
c += s.charAt(i);
i++;
}
return c;
}
public static void main(String... s)
{
System.out.println(LTrim("    i am an indian"));
}
}
class StringDemo7
{
static String RTrim(String s)
{
s = StringDemo4.Reverse(s);
s = StringDemo6.LTrim(s);
s = StringDemo4.Reverse(s);
return s;
}
public static void main(String... s)
{
System.out.println(RTrim("    i am an indian    "));
}
}
class StringDemo8
{
static String AllTrim(String s)
{
s = StringDemo6.LTrim(s);
s = StringDemo7.RTrim(s);
return s;
}
public static void main(String... s)
{
System.out.println(AllTrim("    i am an indian"));
}
}