Java实现Grep

grep.java

import java.io.*;  public class grep{      public static void main(String [] args) throws IOException{          if(args.length<1){              System.out.println("zu wenige Parameter");              throw new IllegalArgumentException("zu wenig Parameter!");          }          boolean reversed =false;          String pattern;          String sfile ="";          try{          if(args[0].equals("-v")){              reversed = true;              pattern =args[1];              if(args.length>2){                  sfile = args[2];              }          }else{              pattern = args[0];              if(args.length==2){                  sfile = args[1];              }          }          }catch(IndexOutOfBoundsException ex){              System.out.println("Irgendwas ist beim verarbeiten der Parameter schiefgegangen: " + ex);              return;          }          if (!(sfile.equals(""))){              File myfile;              try{                  myfile = new File(sfile);              }catch(NullPointerException ex){                  System.out.println("uhhps das sollte nicht passieren: " + ex);                  return;              }              BufferedReader myreader;              try{              myreader = new BufferedReader(new FileReader(myfile));              }catch(FileNotFoundException ex){                  System.out.println("File Not Found: " + ex);                  return;              }              search(myreader, reversed, pattern);          }else{              BufferedReader myreader = new BufferedReader(new InputStreamReader(System.in));              try{                  search(myreader, reversed, pattern);              }catch(IOException ex){                  System.out.println("IO Fehler: " +ex);              }          }        }      private static void search(BufferedReader myreader, boolean reversed, String pattern) throws IOException{          //System.out.println("Suche nach: " + pattern);          while(myreader.ready()){              String sline = myreader.readLine();              if (reversed){                  if(!sline.contains(pattern)){                      System.out.println(sline);                  }              }else{                  if (sline.contains(pattern)){                      System.out.println(sline);                  }              }          }      }  }