and what should the answer for "asu" be?

int num = Integer.parseInt(parseString)

which would be correct, if the String to parse was, for instance,
String toParse = "97";
int num = Integer.parseInt(toParse);

but with an input-String like "asu", like in the example he gives us, this will lead to the necessary exceptions, since "asu" is not recognized as an Integer value

use the following code to convert any string to integer.

import java.io.*;

public class Strng_to_intg{
public static void main(String[] args) throws IOException
{

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int s=br.read();
System.out.println(s);
}
}

try this code to convert any string to int even the string "asu".

That is absolutely not the way to convert a String to an int.

Could you suggest me any other way of converting a string to an ineger?

If you read the posts above, it has already been answered.

but i have tested every post on my netbeans ide it does not work.
The code which i have posted has been tested and verified on my ide and it does convert "asu" to 97.

97 is the byte value of 'a'. Your read() call just got a single byte and converted it to int.

In any case, it's irrelevant. Without a stated encoding expectation, "asu" cannot be converted to int. Integer.parseInt() will convert a valid integer string to an int value. If you want to convert some other string to an int, there are many different ways to do so, but they are specific encoding methods - not just a general api call or statement.