public class StringDemo

public class StringDemo{
    public static void main(String args[]){
        String s1="this is my original string";
        String sd="original";
        if (s1.startsWith(sd)) 
            s1=s1.substring(sd.length());
        else
            if(s1.endsWith(sd)) 
                s1=s1.substring(0,s1.length()-sd.length());
            else
            {
                int index=s1.indexOf(sd); 
                if(index!=-1)
                {
                    String s2=s1.substring(0,index); 
                    String s3=s1.substring(index+sd.length()); 
                    s1=s2+s3;
                }
                else
                System.out.println("string /""+sd+"/" not found");
            }
        System.out.println(s1);
    }
}