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如果你的项目是maven工程,首先在pom.xml中添加commons-lang3包的依赖
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.4</version>
</dependency>
字符串为空判断
import org.apache.commons.lang3.StringUtils;
public class StringUtilsMain {
public static void main(String[] args) {
//isNotEmpty =!isEmpty
boolean a =StringUtils.isEmpty("");//true
boolean a1=StringUtils.isEmpty(" ");//false,注意和isBlank(" ")结果相反
boolean a2=StringUtils.isEmpty(null);//true
boolean b =StringUtils.isNotEmpty("");//false
boolean b1=StringUtils.isNotEmpty(" ");//true
boolean b2=StringUtils.isNotEmpty(null);//false
//isNotBlank =!isBlank
boolean c =StringUtils.isBlank("");//true
boolean c1=StringUtils.isBlank(" ");//true,注意和isEmpty(" ")结果相反
boolean c2=StringUtils.isBlank(null);//true
boolean c3=StringUtils.isBlank("\t \n \f \r");//true //对于制表符、换行符、换页符、回车符识别为了空白符
boolean c4=StringUtils.isBlank("\b");//false //"\b"为单词边界符
boolean d =StringUtils.isNotBlank("");//false
boolean d1=StringUtils.isNotBlank(" ");//false
boolean d2=StringUtils.isNotBlank(null);//false
//isAnyBlank和isAnyEmpty是多维判断是否为空
//isNoneBlank = !isAnyBlank;isNoneEmpty = !isAnyEmpty
boolean e =StringUtils.isAnyBlank("","java","java");//true
boolean e2=StringUtils.isAnyBlank(" ","java","java");//true,注意和isAnyEmpty(" ","java","java")结果相反
boolean f =StringUtils.isAnyEmpty("","java","java");//true
boolean f1=StringUtils.isAnyEmpty(" ","java","java");//false,注意和isAnyBlank(" ","java","java")结果相反
//isWhitespace方法用于判断指定字符是否为空白字符,空白符包含:空格、tab键、换行符。
boolean g =StringUtils.isWhitespace(null);//false
boolean g1=StringUtils.isWhitespace("");//true
boolean g2=StringUtils.isWhitespace(" ");//true
boolean g3=StringUtils.isWhitespace("\t");//true
boolean g4=StringUtils.isWhitespace("\n");//true
}
}
综上结果:
isEmpty判断的条件: str == null || str.length == 0
isBlank判断的条件:str == null || str.length == 0 || str.trim().length == 0
isNotEmpty :判断某字符串是否非空
isNotBlank:判断某字符串是否不为空且长度不为0且不由空白符(whitespace)构成