Java字符串toUpperCase() _字符串toUpperCase()

本文概述

Java String toUpperCase()方法示例
Java String toUpperCase（Locale locale）方法示例2

Java字符串toUpperCase()方法以大写字母返回字符串。换句话说, 它将字符串的所有字符转换为大写字母。
toUpperCase()方法与toUpperCase（Locale.getDefault()）方法相同。它在内部使用默认语言环境。
内部实施

public String toUpperCase(Locale locale) { if (locale == null) { throw new NullPointerException(); }int firstLower; final int len = value.length; /* Now check if there are any characters that need to be changed. */ scan: { for (firstLower = 0 ; firstLower < len; ) { int c = (int)value[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[len]; /* 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, 0, 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 < len; i += srcCount) { srcChar = (int)value[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(result, 0, len + resultOffset); }

签名
toUpperCase()方法有两种变体。字符串toUpperCase()方法的签名或语法如下：

public String toUpperCase() public String toUpperCase(Locale locale)

toUpperCase()的第二个方法变体, 使用给定Locale的规则将所有字符转换为大写。
退货
大写字母的字符串。
Java String toUpperCase()方法示例

public class StringUpperExample{ public static void main(String args[]){ String s1="hello string"; String s1upper=s1.toUpperCase(); System.out.println(s1upper); }}

立即测试
【Java字符串toUpperCase()】输出：

HELLO STRING

Java String toUpperCase（Locale locale）方法示例2

import java.util.Locale; public class StringUpperExample2 { public static void main(String[] args) { String s = "hello string"; String turkish = s.toUpperCase(Locale.forLanguageTag("tr")); String english = s.toUpperCase(Locale.forLanguageTag("en")); System.out.println(turkish); //will print I with dot on upper side System.out.println(english); } }

输出：