学习java第24天

1.文件类

*创建File类对象

File f；

f = new File ("a.java");

f = new File ("C:\\nie\\","a.java");

*File类提供了实现目录管理功能的方法

File path = new File("C:\\nie\\");

File f = new File(path,"a.java");

2.列出所有文件

import java.io.*;
class  ListAllFiles
{
 public static void main(String[] args){
  ListFiles( new File( "c:\\workspace"));
 }

 public static void ListFiles( File dir ){
  if( !dir.exists() || ! dir.isDirectory() ) return;
  
  String [] files = dir.list();
  for( int i=0; i<files.length; i++){
   File file = new File( dir, files[i] );
   if( file.isFile() ){
    System.out.println(
     dir + "\\" + file.getName() + "\t" + file.length() );
   }else{
    System.out.println(
     dir + "\\" + file.getName() + "\t<dir>" );
    
    ListFiles( file );  //对于子目录,进行递归调用
   }
  }
 }
}

3.Pattern类

import java.util.regex.*;
public class RegexSplitter {
 public static void main(String[] args) throws Exception {
  Pattern p = Pattern.compile( "[, \\s]+");
  String[] result =
   p.split( "one,two, three   four ,  five ");
  for (int i=0; i<result.length; i++)
   System.out.println(result[i]);
 }
}

4.匹配

import java.util.regex.*;
public class RegexEmailValidate {
 public static void main(String[] args)
   throws Exception {
  String pattern = "^[^@]+@[\\w]+(\\.[\\w]+)*$";
  String email = "[email protected]";
  boolean ok = Pattern.matches( pattern, email );
  System.out.println( ok );
 }
}

5.Matcher类

mport java.util.regex.*;
public class RegexReplacement {
 public static void main(String[] args)
   throws Exception {
  Pattern pattern = Pattern.compile("cat");
  Matcher matcher = pattern.matcher(
   "one cat, two cats in the yard");
  StringBuffer sb = new StringBuffer();
  while(matcher.find()) {
   matcher.appendReplacement(sb, "big $0");
  }
  matcher.appendTail(sb);
  System.out.println(sb.toString());
 }
}

 

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