本文介绍了 Apache Commons Lang 库中的 StringUtils 类提供的多种实用字符串操作方法，包括检查空字符串、缩写字符串、查找嵌套字符串等。通过具体示例展示了如何使用这些方法简化字符串处理任务。
org.apache.commons.lang.StringUtils中提供许多有用的字符串操作方法，了解这些方法，我们可以避免许多不必要的重复工作。下面介绍其中比较有用的几个方法：
检查空字符串：
检查空字符串：
- StringUtils.isBlank(String str);
- StringUtils.isNotBlank(String str);
缩写字符串：
- String test = " This is a test of the abbreviation. "
- System.out.println( StringUtils.abbreviate( test, 10 ) );
- [Console输出]
- This is
查找嵌套字符串：
- String htmlContent = " <html>/n " +
- " <head>/n " +
- " <title>Test Page</title>/n " +
- " </head>/n " +
- " <body>/n " +
- " <p>This is a TEST!</p>/n " +
- " </body>/n " +
- " </html> " ;
- // Extract the title from this XHTML content
- String title = StringUtils.substringBetween(htmlContent, " <title> " , " </title> " );
- System.out.println( " Title: " + title );
- [Console输出]
- Title: Test Page
验证字符串：
- String test1 = " ORANGE " ;
- String test2 = " ICE9 " ;
- String test3 = " ICE CREAM " ;
- String test4 = " 820B Judson Avenue " ;
- //判断字母
- boolean t1val = StringUtils.isAlpha( test1 ); // returns true
- //判断是不是字母数字
- boolean t2val = StringUtils.isAlphanumeric( test2 ); // returns true
- //字母空格
- boolean t3val = StringUtils.isAlphaSpace( test3 ); // returns true
- //字母数字空格
- boolean t4val =
- StringUtils.isAlphanumericSpace( test4 ); // returns true
计算字符串出现频率：
1. File manuscriptFile = new File( " manuscript.txt " );
2. Reader reader = new FileReader( manuscriptFile );
3. StringWriter stringWriter = new StringWriter( );
4. while ( reader.ready( ) ) { writer.write( reader.read( ) ); }
5. String manuscript = stringWriter.toString( );
6. // Convert string to lowercase
7. manuscript = StringUtils.lowerCase(manuscript);
8. // count the occurrences of "futility"
9. int numFutility = StringUtils.countMatches( manuscript, " futility " );
比较不同字符串：
- int dist = StringUtils.getLevenshteinDistance( " Word " , " World " );
- String diff = StringUtils.difference( " Word " , " World " );
- int index = StringUtils.indexOfDifference( " Word " , " World " );
- System.out.println( " Edit Distance: " + dist );
- System.out.println( " Difference: " + diff );
- System.out.println( " Diff Index: " + index );
- [Console输出]
- Edit Distance: 2
- Difference: ld
- Diff Index: 3
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