toUpperCase

Programação Java
#1

Olá, bom dia!!

Preciso saber como funciona este método, não o que ele faz e sim como ele faz…

#2

Este é o método toUpperCase encontrado na java.lang.String.
Se você estiver no eclipse, basta adicionar a máquina virtual da pasta jdk que os códigos fonte aparecem.
O eclipse reconhece automaticamente a jre como default.

[code]public String toUpperCase(Locale locale) {
if (locale == null) {
throw new NullPointerException();
}

    int     firstLower;

/* Now check if there are any characters that need to be changed. */
scan: {
    for (firstLower = 0 ; firstLower < count; ) {
	int c = (int)value[offset+firstLower];
	int srcCount;
	if ((c >= Character.MIN_HIGH_SURROGATE) &&
	    (c <= Character.MAX_HIGH_SURROGATE)) {
	    c = codePointAt(firstLower);
	    srcCount = Character.charCount(c);
	} else {
	    srcCount = 1;
	}
	int upperCaseChar = Character.toUpperCaseEx(c);
	if ((upperCaseChar == Character.ERROR) ||
	    (c != upperCaseChar)) {
	    break scan;
	}
	firstLower += srcCount;
    }
    return this;
}

    char[]  result       = new char[count]; /* may grow */
int     resultOffset = 0;  /* result may grow, so i+resultOffset
			    * is the write location in result */

/* Just copy the first few upperCase characters. */
System.arraycopy(value, offset, result, 0, firstLower);

String lang = locale.getLanguage();
boolean localeDependent =
        (lang == "tr" || lang == "az" || lang == "lt");
    char[] upperCharArray;
    int upperChar;
    int srcChar;
    int srcCount;
    for (int i = firstLower; i < count; i += srcCount) {
    srcChar = (int)value[offset+i];
    if ((char)srcChar >= Character.MIN_HIGH_SURROGATE &&
        (char)srcChar <= Character.MAX_HIGH_SURROGATE) {
	srcChar = codePointAt(i);
	srcCount = Character.charCount(srcChar);
    } else {
        srcCount = 1;
    }
        if (localeDependent) {
            upperChar = ConditionalSpecialCasing.toUpperCaseEx(this, i, locale);
        } else {
            upperChar = Character.toUpperCaseEx(srcChar);
        }
        if ((upperChar == Character.ERROR) ||
            (upperChar >= Character.MIN_SUPPLEMENTARY_CODE_POINT)) {
            if (upperChar == Character.ERROR) {
                if (localeDependent) {
                    upperCharArray =
                        ConditionalSpecialCasing.toUpperCaseCharArray(this, i, locale);
                } else {
                    upperCharArray = Character.toUpperCaseCharArray(srcChar);
                }
            } else if (srcCount == 2) {
	    resultOffset += Character.toChars(upperChar, result, i + resultOffset) - srcCount;
	    continue;
            } else {
                upperCharArray = Character.toChars(upperChar);
	}

            /* Grow result if needed */
            int mapLen = upperCharArray.length;
	if (mapLen > srcCount) {
                char[] result2 = new char[result.length + mapLen - srcCount];
                System.arraycopy(result, 0, result2, 0,
                    i + resultOffset);
                result = result2;
	}
            for (int x=0; x<mapLen; ++x) {
                result[i+resultOffset+x] = upperCharArray[x];
            }
            resultOffset += (mapLen - srcCount);
        } else {
            result[i+resultOffset] = (char)upperChar;
        }
    }
    return new String(0, count+resultOffset, result);
}[/code]
#3