Java字符串驼峰与下换线格式转换如何实现

下面是自己写的三个方法,直接类名.方法即可调用,注意此处未做异常处理.

1.下划线转驼峰 lowerLineToHump()

2.首字母大写 capitalizeTheFirstLetter()

3.驼峰转下划线 humpToLowerLine()

package yang.demo.justwrite;

import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class VariableNameConversion {

  private static Pattern humpPattern = Pattern.compile("[A-Z]");

  public static void main(String[] args) {

    System.out.println(lowerLineToHump("NAME_AND_addREsS"));
    System.out.println(capitalizeTheFirstLetter("nAMe"));
    System.out.println(humpToLowerLine("nameAndAddress"));

  }

  
  public static String lowerLineToHump(String lowerLineAndUppercaseStr) {
    //拆分成数组
    String[] eachStr = lowerLineAndUppercaseStr.split("_");
    StringBuilder resStr = new StringBuilder();
    String firstStr = "";
    String tempStr = "";
    for (int i = 0; i < eachStr.length; i++) {
      //第一个数组全部小写
      if (i == 0) {
 firstStr = eachStr[0].toLowerCase();
 resStr.append(firstStr);
      } else {
 //以后的数组首字母大写
 tempStr = capitalizeTheFirstLetter(eachStr[i]);
 resStr.append(tempStr);
      }
    }

    return resStr.toString();
  }

  
  public static String capitalizeTheFirstLetter(String str) {
    char firstChar = str.toUpperCase().charAt(0);
    String nextStr = str.toLowerCase().substring(1);
    return firstChar + nextStr;
  }

  
  public static String humpToLowerLine(String humpStr, boolean ... defaultUppercaseAndTrueLowercase) {
    Matcher matcher = humpPattern.matcher(humpStr);
    StringBuffer sb = new StringBuffer();
    while (matcher.find()) {
      matcher.appendReplacement(sb, "_" + matcher.group(0).toLowerCase());
    }
    matcher.appendTail(sb);

    //如果第二个形参为true 转为大写
    if (defaultUppercaseAndTrueLowercase.length>=1 && defaultUppercaseAndTrueLowercase[0]){
      return sb.toString().toUpperCase();
    }
    return sb.toString();
  }

}

输出结果

nameAndAddress
Name
name_and_address

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