打印句子中每个单词的首字母

Question

I need to extract the first character from each word present in the sentence.
the output should be : JaJwuth but it coming : JJJJJaaaaJJJJJwwwwwuuutttthhhhh

Here is my code:

class new_word {
    public static void main(String args[]) {

        String s = "Jack and Jill went up the hill";
        s = ' ' + s; /* adding space before the string */
        char ch;
        int i, l;
        l = s.length();
        for (i = 0; i < l; i++) {
            if (s.charAt(i) == (' '))
                ch = s.charAt(i + 1);
        }
        System.out.println(ch); /* here the error appears */
    }
}

Please help me understand what I did wrongly, thanks.the output should be:JaJwuth

Answer 1

You have to initialize ch

change

char ch;

to

char ch=' ' ;

Answer 2

Other than the initialization problem that you are getting for char ch; , which you fix by initializing it with an empty char ( char ch = ' '; ), this is probably what you are trying to do (without using char ch):

class new_word {
    public static void main(String args[]) {

        String s = "Jack and Jill went up the hill";
        s = ' ' + s; /* adding space before the string */
        int strLen = s.length();
        for (int i = 0; i < strLen; i++) {
            if (s.charAt(i) == (' '))
                System.out.println(s.charAt(i + 1));
        }
    }
}

Output:

J
a
J
w
u
t
h

Note: The System.out.println(...) was outside the for loop in the question.

Answer 3

您想初始化ch因为在实例中for循环未运行（例如，当i> = 1时），则ch将永远不会初始化，然后您尝试打印出未初始化的变量

char ch ='\0';