grep的java源程序_Java实现Grep
Java實現(xiàn)Grep
1.[代碼]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);
}
}
}
}
}
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