java - 在android中将CharSequence的首字母更改为大写

Question

看起来很简单，但它有很多错误 我试过这种方式:

 String s = gameList[0].toString();
s.replaceFirst(String.valueOf(s.charAt(0)),String.valueOf(Character.toUpperCase(s.charAt(0))) );

并抛出异常

我的另一个尝试是:

String s = gameList[0].toString();
char c = Character.toUpperCase(gameList[0].charAt(0));
gameList[0] = s.subSequence(1, s.length());

这个也抛出一个异常

Answer 1

/**
 * returns the string, the first char lowercase
 *
 * @param target
 * @return
 */
public final static String asLowerCaseFirstChar(final String target) {

    if ((target == null) || (target.length() == 0)) {
        return target; // You could omit this check and simply live with an
                       // exception if you like
    }
    return Character.toLowerCase(target.charAt(0))
            + (target.length() > 1 ? target.substring(1) : "");
}

/**
 * returns the string, the first char uppercase
 *
 * @param target
 * @return
 */
public final static String asUpperCaseFirstChar(final String target) {

    if ((target == null) || (target.length() == 0)) {
        return target; // You could omit this check and simply live with an
                       // exception if you like
    }
    return Character.toUpperCase(target.charAt(0))
            + (target.length() > 1 ? target.substring(1) : "");
}