520. Detect Capital 

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class Solution {
    public boolean detectCapitalUse(String word) {
        int upperCaseCount = 0;
        for (int i = 0; i < word.length(); i++) {
            if (Character.isUpperCase(word.charAt(i))) {
                upperCaseCount++;
            }
        }

        return upperCaseCount == word.length() || upperCaseCount == 0 || (Character.isUpperCase(word.charAt(0)) && upperCaseCount == 1);
    }
}

References

520. Detect Capital