Android开发之字符串各种判断-StringUtils

判断字符串是否为null或者空

public static boolean isEmpty(final CharSequence s) {
        return s == null || s.length() == 0;
}

判断去除空格后的字符串是否为null或者空

public static boolean isTrimEmpty(final String s) {
        return (s == null || s.trim().length() == 0);
}

判断字符串是否为null或者空

public static boolean isSpace(final String s) {
        if (s == null) return true;
        for (int i = 0, len = s.length(); i < len; ++i) {
            if (!Character.isWhitespace(s.charAt(i))) {
                return false;
            }
        }
        return true;
}

判断忽略大小写情况下，字符串是否equals

public static boolean equalsIgnoreCase(final String s1, final String s2) {
        return s1 == null ? s2 == null : s1.equalsIgnoreCase(s2);
}

避免字符串null时，空指针问题

 public static String null2Length0(final String s) {
        return s == null ? "" : s;
 }

判断字符串长度

public static int length(final CharSequence s) {
        return s == null ? 0 : s.length();
}

字符串首字母大写

public static String upperFirstLetter(final String s) {
        if (isEmpty(s) || !Character.isLowerCase(s.charAt(0))) return s;
        return String.valueOf((char) (s.charAt(0) - 32)) + s.substring(1);
}

首字母小写

public static String lowerFirstLetter(final String s) {
        if (isEmpty(s) || !Character.isUpperCase(s.charAt(0))) return s;
        return String.valueOf((char) (s.charAt(0) + 32)) + s.substring(1);
}

判断字符串是否纯数字

public static boolean isNumeric(String str){
    for (int i = str.length();--i>=0;){  
        if (!Character.isDigit(str.charAt(i))){
            return false;
        }
    }
    return true;
}

//使用ASCII码判断
public static boolean isNumeric(String str){
    for(int i=str.length();--i>=0;){
        int chr=str.charAt(i);
        if(chr<48 || chr>57)
            return false;
    }
   return true;
}
//使用正则，（推荐）
public static boolean isInteger(String str) {  
        Pattern pattern = Pattern.compile("^[-\\+]?[\\d]*$");  
        return pattern.matcher(str).matches();  
}
//使用正则
public final static boolean isNumeric(String s) {
    if (s != null && !"".equals(s.trim()))
        return s.matches("^[0-9]*$");
    else
        return false;
}     

判断字符串是否整数

public static boolean isNumeric(String str){
    for (int i = str.length();--i>=0;){  
        if (!Character.isDigit(str.charAt(i))){
            return false;
        }
    }
    return true;
}

public boolean isNumeric(String str){ 
   Pattern pattern = Pattern.compile("[0-9]*"); 
   Matcher isNum = pattern.matcher(str);
   if( !isNum.matches() ){
       return false; 
   } 
   return true; 
}

判断字符串是否纯字母

public boolean isLetter（String str）｛
    Pattern pattern = Pattern.compile("[a-zA-Z] + "); 
    Matcher isLetter = pattern.matcher(str);
    if( !isLetter.matches() ){
       return false; 
    }
｝

判断字符串是否手机号码

public boolean isMobilePhone(String mobiles) {
    Pattern p = Pattern.compile("^((13[0-9])|(15[^4,\\D])|(18[0-9]))\\d{8}$");
    Matcher m = p.matcher(mobiles);
    return m.matches();
}

判断提取字符串中手机号码

private static String checkNum(String num){
      if(num == null || num.length() == 0){return "";}
      Pattern pattern = Pattern.compile("(?<!\\d)(?:(?:1[358]\\d{9})|(?:861[358]\\d{9}))(?!\\d)"); 
      Matcher matcher = pattern.matcher(num); 
      StringBuffer bf = new StringBuffer(64); 
      while (matcher.find()) { 
        bf.append(matcher.group()).append(","); 
      } 
      int len = bf.length(); 
      if (len > 0) { 
        bf.deleteCharAt(len - 1); 
      } 
      return bf.toString();
 } 

判断字符串，手机号码隐藏中间四位

public static String getSafePhone（String phone）｛
     if（phone == null || phone.length（） == 0） return;
     String phoneNumber = phone.replaceAll("(\\d{3})\\d{4}(\\d{4})","$1****$2");
     return phoneNumber;
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判断字符串，银行卡号隐藏中间八位

public static String getSafeCardNum（String bankCard）｛
        if（bankCard == null || bankCard.length（） == 0） return;
        int hideLength = 8;//替换位数
        int sIndex = bankCard.length()/2 - hideLength/2;
        String replaceSymbol = "*";
        StringBuilder sBuilder = new StringBuilder();
        for (int i = 0; i<bankCard.length();i++){
            char number = bankCard.charAt(i);
            if (i >= sIndex-1 && i<sIndex+hideLength){
                sBuilder.append(replaceSymbol);
            }else {
                sBuilder.append(number);
            }
        }
        return sBuilder.toString();
｝