Common-lang 研究 -- StringUtils 1-优快云博客

本文通过实例展示了Apache Commons Lang库中的字符串工具方法，包括判断字符串是否为空或空白的功能。通过对不同类型的字符串进行测试，验证了StringUtils类中isEmpty, isNotEmpty, isBlank及isNotBlank方法的行为。

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官方网站
http://commons.apache.org/lang/
下载地址
http://commons.apache.org/lang/download_lang.cgi
版本
commons-lang3-3.0-beta

测试方法


public static boolean isEmpty(CharSequence cs)
public static boolean isNotEmpty(CharSequence cs)

测试代码


String emptyString = "";
String nullString = null;
String blankString1 = " ";
String blankString2 = "\t\r\f\n";
String normalString = "Hello World!";

System.out.println("----------------------isEmpty------------------------------");
System.out.println("emptyString \t--> " + StringUtils.isEmpty(emptyString));
System.out.println("nullString \t--> " + StringUtils.isEmpty(nullString));
// 注意在 StringUtils 中空格作非空处理
System.out.println("blankString1 \t--> " + StringUtils.isEmpty(blankString1));
System.out.println("blankString2 \t--> " + StringUtils.isEmpty(blankString2));
System.out.println("normalString \t--> " + StringUtils.isEmpty(normalString));

System.out.println("----------------------isNotEmpty---------------------------");

System.out.println("emptyString \t--> " + StringUtils.isNotEmpty(emptyString));
System.out.println("nullString \t--> " + StringUtils.isNotEmpty(nullString));
System.out.println("blankString1 \t--> " + StringUtils.isNotEmpty(blankString1));
System.out.println("blankString2 \t--> " + StringUtils.isNotEmpty(blankString2));
System.out.println("normalString \t--> " + StringUtils.isNotEmpty(normalString));

测试结果


----------------------isEmpty---------------------------------
emptyString 	--> true
nullString 	--> true
blankString1 	--> false
blankString2 	--> false
normalString 	--> false
----------------------isNotEmpty------------------------------
emptyString 	--> false
nullString 	--> false
blankString1 	--> true
blankString2 	--> true
normalString 	--> true

测试方法


public static boolean isBlank(CharSequence cs)
public static boolean isNotBlank(CharSequence cs)

测试代码


String emptyString = "";
String nullString = null;
String blankString1 = " ";
String blankString2 = "\t\r\f\n";
String normalString = "Hello World!";

System.out.println("----------------------isBlank------------------------");
System.out.println("emptyString \t--> " + StringUtils.isBlank(emptyString));
System.out.println("nullString \t--> " + StringUtils.isBlank(nullString));
System.out.println("blankString1 \t--> " + StringUtils.isBlank(blankString1));
System.out.println("blankString2 \t--> " + StringUtils.isBlank(blankString2));
System.out.println("normalString \t--> " + StringUtils.isBlank(normalString));

System.out.println("----------------------isNotBlank----------------------");

System.out.println("emptyString \t--> " + StringUtils.isNotBlank(emptyString));
System.out.println("nullString \t--> " + StringUtils.isNotBlank(nullString));
System.out.println("blankString1 \t--> " + StringUtils.isNotBlank(blankString1));
System.out.println("blankString2 \t--> " + StringUtils.isNotBlank(blankString2));
System.out.println("normalString \t--> " + StringUtils.isNotBlank(normalString));

测试结果


----------------------isBlank------------------------
emptyString 	--> true
nullString 	--> true
blankString1 	--> true
blankString2 	--> true
normalString 	--> false
----------------------isNotBlank----------------------
emptyString 	--> false
nullString 	--> false
blankString1 	--> false
blankString2 	--> false
normalString 	--> true