Some error find whats the problem

import java.io.*; public class Replace { public void main()throwsIoException { InputStreamReader = new InputStreamReader(System.in); BufferReader br=new BufferReader(z); System.out.println("Enter A String:"); String s=br.readline(); System.out.println(("Enter First Word:"); String w1=br.readline(); System.out.println("Enter Second Word:"); String w2=br.readline(); String str=" "; String st=" "; for(int i=0;i<=s.lenth();i++); { char ch=s.charAt(i); if(ch!=' ') { str=str+ch; { if(str.equals(w1)) { st=s.replace(w1,w2); } System.out.println(st); } } } output of above code Enter A String This is a flower Enter First Word is Enter Second Word was after replace string will be This was a flower note:- The word 'is' is existing in string so it's replace with second word 'was'.

Respected sir i've a problem with above code i unable to understand that what's the problem in above code because output is not so rightly so plz help me and follow these instruction 1 do not use Stringtokenizer 2 do not use reverse method 3 do not use StringBufferReader 4 do not use Split method