Problem with RandomAccessFile

Question

public static void main(String[] args) throws FileNotFoundException, IOException
        String str="Abcdef University";
        RandomAccessFile raf = new RandomAccessFile("C:/dos.txt","rw");
        raf.seek(raf.length());
        raf.writeBytes(str);
        raf.close();
Could anyone please tell me how do I do the following
1. I need to convert the contents of C:/dos.txt to a string
2. Need to check whether the value of str is present inside the file C:/dos.txt
Thanks in advance

Answer 1

1. Read the contents of your file into memory:
import java.io.BufferedReader;
import java.io.FileReader;
BufferedReader in = new BufferedReader(new FileReader("c:/dos.txt"));
StringBuffer sb = new StringBuffer();
while(true) {
string s = in.readLine();
if(s == null) {
break;
sb.append(s);
sb.append('\n');
in.close();
// sb.toString() is the contents of your file. Not the smartest thing to do here
// because your file could be enormous and there is a limit to the size of
// strings that you can have in java. Finding substrings in large files is
// a search algorithm problem that is beyond the scope of a simple java
// beginner's forum.
2. Find your string in the contents of the file.
int index = sb.toString().indexOf("your string");
if(index > -1) {
// substring was found!
Does this help? You don't need to use a RandomAccessFile to append data to your file, but if it works, then good job. There are lots of ways to do I/O in Java.
None of this code catches exceptions. You would be smart to add that code so that you can handle errors that occur while reading the file.