将一行单词从小写转换为大写

Question

I would like to convert a line of words, including punctuation and spaces, from lower case to upper case. My method to deal with the question is to firstly store the sentence in String form, then apply the "toUpperCase" Java class to it like this:

public static void main(String[] args) {

    Scanner in = new Scanner(System.in);
    String input = in.next();
    String upper = input.toUpperCase();

    System.out.println(upper);

}

But it reads a sentence with spaces or punctuation in the middle, something would come out like this:

you are so smart!
YOU

How to solve this problem? Can anyone give me some advice? Thanks in advance.

Answer 1

Change

 String input = in.next();

In to

 String input = in.nextLine(); // you need to take entire line

Now

 Scanner in = new Scanner(System.in);
 String input = in.nextLine();
 String upper = input.toUpperCase();

 System.out.println(upper);

Out out:

 YOU ARE SO SMART

More info: Read next() and nextLine()

Answer 2

in.read() will return you the next token (as per javadoc , a complete token is preceded and followed by input that matches the delimiter pattern , , which by defaul matches a whitespace), not the next line.

Change

String input = in.next();

to

String input = in.nextLine();

If you still want to stick to the " in.next() approach" and get the entire line, you can change the delimiter pattern. Like this:

Scanner in = new Scanner(System.in).useDelimiter("\n");

In this case, a token will be everthing that ends with a line-breaking character ( \\n ) and in.next() will return you the entire line.

Answer 3

 String input = in.next();

When you store input by using .next(), whenever the scanner encounters a whitespace it stops reading for input. Whereas if you use

 String input = in.nextLine();

the scanner will input the complete line entered by the user. In simple terms, next() - to input a word nextLine() - to input a sentense