我使用Java从用户获得一个字符串输入。我试着让输入的第一个字母大写。
我试了一下:
String name;
BufferedReader br = new InputStreamReader(System.in);
String s1 = name.charAt(0).toUppercase());
System.out.println(s1 + name.substring(1));
这导致了以下编译错误:
类型不匹配:不能从InputStreamReader转换为BufferedReader 不能在基本类型char上调用toUppercase()
当前回答
使用此实用程序方法将每个单词的第一个字母大写。
String capitalizeAllFirstLetters(String name)
{
char[] array = name.toCharArray();
array[0] = Character.toUpperCase(array[0]);
for (int i = 1; i < array.length; i++) {
if (Character.isWhitespace(array[i - 1])) {
array[i] = Character.toUpperCase(array[i]);
}
}
return new String(array);
}
其他回答
为了避免异常(IndexOutOfBoundsException或NullPointerException当使用子字符串(0,1)为空或空字符串时)，您可以使用regex ("^.") (自Java 9起):
try(BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
String name = reader.readLine();
name = Pattern.compile("^.") // regex for the first character of a string
.matcher(name)
.replaceFirst(matchResult -> matchResult.group().toUpperCase());
System.out.println(name);
} catch(IOException ignore) {}
来自Apache Commons的wordutil .capitalize(java.lang.String)。
谢谢，我已经阅读了一些评论，并带来了以下内容
public static void main(String args[])
{
String myName = "nasser";
String newName = myName.toUpperCase().charAt(0) + myName.substring(1);
System.out.println(newName );
}
我希望它能有所帮助 祝你好运
你可以试试这个
/**
* capitilizeFirst(null) -> ""
* capitilizeFirst("") -> ""
* capitilizeFirst(" ") -> ""
* capitilizeFirst(" df") -> "Df"
* capitilizeFirst("AS") -> "As"
*
* @param str input string
* @return String with the first letter capitalized
*/
public String capitilizeFirst(String str)
{
// assumptions that input parameter is not null is legal, as we use this function in map chain
Function<String, String> capFirst = (String s) -> {
String result = ""; // <-- accumulator
try { result += s.substring(0, 1).toUpperCase(); }
catch (Throwable e) {}
try { result += s.substring(1).toLowerCase(); }
catch (Throwable e) {}
return result;
};
return Optional.ofNullable(str)
.map(String::trim)
.map(capFirst)
.orElse("");
}
下面的例子也将特殊字符后的单词大写，如[/-]
public static String capitalize(String text) {
char[] stringArray = text.trim().toCharArray();
boolean wordStarted = false;
for( int i = 0; i < stringArray.length; i++) {
char ch = stringArray[i];
if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || ch == '\'') {
if( !wordStarted ) {
stringArray[i] = Character.toUpperCase(stringArray[i]);
wordStarted = true;
}
} else {
wordStarted = false;
}
}
return new String(stringArray);
}
Example:
capitalize("that's a beautiful/wonderful life we have.We really-do")
Output:
That's A Beautiful/Wonderful Life We Have.We Really-Do
