patternjavaMinor

Sentence formatting

Submitted by: @import:stackexchange-codereview·Mar 10, 2026·

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formattingsentencestackoverflow

Problem

I wrote this function to format a given sentence via Java, and I'm wondering if there is a better way of doing this without use of external libraries, such as with regex.

public class ChatFormat {

    public static void main(String[] args) {
        String input = "hello, it's a monday today and i think i'll go to the store. and get? some! tea.";
        System.out.println(optimizeText(input));
    }

    public static String optimizeText(String text) {
        char buf[] = text.toLowerCase().toCharArray();
        boolean endMarker = true;
        for (int i = 0; i = 'a' && c  0)
                    last = buf[i - 1];
                if (last == ' ' && (next == ' ' || next == '\'' || next == 0))
                    buf[i] = Character.toUpperCase(c);
            }
        }
        return new String(buf, 0, buf.length);
    }
}

Solution

Inconsistent braces usage

Some of your if statements have enclosing { } but some do not, please standardize and use them throughout. :)

Character comparison

c >= 'a' && c 

I'll prefer to use the ternary operator to set

next and last

 as such, it's a little more compact:

char next = i  1 ? buf[i - 1] : 0;

If-else-if ladder




Since your three

if conditions are mutually exclusive, you can also consider putting them together in one if-else-if

 ladder, e.g.

if (endMarker && Character.isLetter(c)) {
    ...
} else if (c == '.' || c == '!' || c == '?') {
    ...
} else if (c == 'i') {
    ...
}

Use of toLowerCase()




Since you are already operating on a character array, perhaps you can consider converting to lower case letter as the final

else

 branch, i.e.

char buf[] = text.toCharArray();
...
(for loop)
    if (...) {
        ...
    } else if (c == 'i') {
        ...
    } else {
        buf[i] = Character.toLowerCase(c);
    }


This does save one extra copy of the

String

 in lower case, if anything.

Testing



It's fine so far to showcase one example using

public static void main`, but do consider building out some unit tests using a unit testing framework (e.g. TestNG, JUnit):

@Test // TestNG
public void doTest() {
    // Hamcrest matchers
    assertThat(optimizeText("that is its"), equalTo("That is its")); 
    assertThat(optimizeText("i'm"), equalTo("I'm"));
}

Other notes

Your simplified logic doesn't appear to handle sentence structures accurately, but since you seem to be more concerned with the formatting (capitalization), then I guess it's ok.

Code Snippets

char next = i < buf.length - 1 ? buf[i + 1] : 0;
char last = i > 1 ? buf[i - 1] : 0;

if (endMarker && Character.isLetter(c)) {
    ...
} else if (c == '.' || c == '!' || c == '?') {
    ...
} else if (c == 'i') {
    ...
}

char buf[] = text.toCharArray();
...
(for loop)
    if (...) {
        ...
    } else if (c == 'i') {
        ...
    } else {
        buf[i] = Character.toLowerCase(c);
    }

@Test // TestNG
public void doTest() {
    // Hamcrest matchers
    assertThat(optimizeText("that is its"), equalTo("That is its")); 
    assertThat(optimizeText("i'm"), equalTo("I'm"));
}

Context

StackExchange Code Review Q#75201, answer score: 3

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