Java字符串toLowerCase() _字符串toLowerCase()

本文概述

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

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

public String toLowerCase(Locale locale) { if (locale == null) { throw new NullPointerException(); }int firstUpper; final int len = value.length; /* Now check if there are any characters that need to be changed. */ scan: { for (firstUpper = 0 ; firstUpper < len; ) { char c = value[firstUpper]; if ((c > = Character.MIN_HIGH_SURROGATE) & & (c < = Character.MAX_HIGH_SURROGATE)) { int supplChar = codePointAt(firstUpper); if (supplChar != Character.toLowerCase(supplChar)) { break scan; } firstUpper += Character.charCount(supplChar); } else { if (c != Character.toLowerCase(c)) { break scan; } firstUpper++; } } return this; }char[] result = new char[len]; int resultOffset = 0; /* result may grow, so i+resultOffset * is the write location in result *//* Just copy the first few lowerCase characters. */ System.arraycopy(value, 0, result, 0, firstUpper); String lang = locale.getLanguage(); boolean localeDependent = (lang == "tr" || lang == "az" || lang == "lt"); char[] lowerCharArray; int lowerChar; int srcChar; int srcCount; for (int i = firstUpper; 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 || srcChar == '\u03A3') { // GREEK CAPITAL LETTER SIGMA lowerChar = ConditionalSpecialCasing.toLowerCaseEx(this, i, locale); } else if (srcChar == '\u0130') { // LATIN CAPITAL LETTER I DOT lowerChar = Character.ERROR; } else { lowerChar = Character.toLowerCase(srcChar); } if ((lowerChar == Character.ERROR) || (lowerChar > = Character.MIN_SUPPLEMENTARY_CODE_POINT)) { if (lowerChar == Character.ERROR) { if (!localeDependent & & srcChar == '\u0130') { lowerCharArray = ConditionalSpecialCasing.toLowerCaseCharArray(this, i, Locale.ENGLISH); } else { lowerCharArray = ConditionalSpecialCasing.toLowerCaseCharArray(this, i, locale); } } else if (srcCount == 2) { resultOffset += Character.toChars(lowerChar, result, i + resultOffset) - srcCount; continue; } else { lowerCharArray = Character.toChars(lowerChar); }/* Grow result if needed */ int mapLen = lowerCharArray.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] = lowerCharArray[x]; } resultOffset += (mapLen - srcCount); } else { result[i + resultOffset] = (char)lowerChar; } } return new String(result, 0, len + resultOffset); }

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

public String toLowerCase() public String toLowerCase(Locale locale)

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

public class StringLowerExample{ public static void main(String args[]){ String s1="srcmini HELLO stRIng"; String s1lower=s1.toLowerCase(); System.out.println(s1lower); }}

立即测试
输出：

srcmini hello string

Java String toLowerCase（Locale locale）方法示例2此方法还允许我们为各种语言传递语言环境。让我们看下面的示例, 在该示例中, 我们同时获得英语和土耳其语的字符串。

import java.util.Locale; public class StringLowerExample2 { public static void main(String[] args) { String s = "srcmini HELLO stRIng"; String eng = s.toLowerCase(Locale.ENGLISH); System.out.println(eng); String turkish = s.toLowerCase(Locale.forLanguageTag("tr")); // It shows i without dot System.out.println(turkish); } }

输出：