How to pick up a single character from a string using Java?

For example, "this is yahoo answers", from here I want to pick up each single character and convert it into its ASCII val开发者_Python百科ue. How can I do it?

Your question is a bit vague, but probably you meant to want this?

for (char c : "this is yahoo answers".toCharArray()) {
    System.out.println((int) c);
}

This produces the following:

116
104
105
115
32
105
115
32
121
97
104
111
111
32
97
110
115
119
101
114
115

Casting the char to an int will display its codepoint.

   String s = "stackoverflow.com"; 

    for(int i=0; i<s.length(); i++) {
     int ascii = (int) s.charAt(i) ;
     // .....
    }

for(int i = 0; i< theString.length; i++)
  theString.charAt(i);

If you want to support the whole unicode range, including for example the emoticons new in 6.0 (http://unicode.org/Public/6.0.0/charts/versioned/U1F600.pdf), you could try this:

for (int i=0, len=string.length(); i<len; ++i) {
    int codepoint = Character.codePointAt(string, i);
    if (codepoint > Character.MAX_VALUE) {
        ++i;
    }
    System.out.println(codepoint);
}

Otherwise, if you are sure that the input will only be ascii, why not state this assumption in the code like this:

byte[] ascii = string.getBytes("US-ASCII");
for (int i=0, len=ascii.length; i<len; ++i) {
    int ch = ascii[i];
    System.out.println(ch);
}

This should throw a nice exception if the code happens to contain non-ascii characters.