I am a beginer.please help me.thanks.

Question

//The source code is listed below,and questions are also listed.Thanks for reading.
import java.io.*;
public class copyfile{
static public int main(String[] argv){
String srcfile=new String("test.txt");
String destfile=new String("test.backup");
File src=new File(srcfile);
boolean existe=src.exists();
if(!existe){
System.out.println("file "+src.getName()+" is not existe.Please create one first and try again.");
//throws new FileNotFoundException;
//why the above statement is wrong??
System.exit(1);
//boolean create=(File dest=new File(destfile)).createNewFile();
//What's wrong with the above statement???Why??!
File dest=new File(destfile);
try{
boolean create=dest.createNewFile();
}catch(IOException e){
System.exit(1);
}finally{
if(create){
System.out.println("file "+dest.getName()+" was created!");
}else{
System.out.println("file "+dest.getName()+" was already existe.");
}//end_finally
try{
copy(src,dest);
}catch(IOException e){
System.out.println("Caught one io exception");
return 1;
static void copy(File src,File dest) throws IOException{
InputStream in=new FileInputStream(src);
OutputStream out=new FileOutputStream(dest);
byte[] buf=new byte[1024];
int len=0;
while((len=in.read(buf))>0)
out.write(buf,0,len);
in.close();
out.close();
}//end_copy
// by longwen

Answer 1

//The source code is listed below,and questions are also listed.Thanks for reading.
import java.io.*;
public class copyfile{
    static public int main(String[] argv){
       String srcfile=new String("test.txt");
       String destfile=new String("test.backup");
       File src=new File(srcfile);
      boolean existe=src.exists();
    if(!existe){
       System.out.println("file "+src.getName()+" is not existe.Please create one first and try again.");
         //throws new FileNotFoundException;
//why the above statement is wrong??
System.exit(1);
    //boolean create=(File dest=new File(destfile)).createNewFile();
//What's wrong with the above statement???Why??!
File dest=new File(destfile);
    try{
        boolean create=dest.createNewFile();
       }catch(IOException e){
               System.exit(1);
       }if(create){
           System.out.println("file "+dest.getName()+" was created!");
        }else{
            System.out.println("file "+dest.getName()+" was already existe.");
    try{
        copy(src,dest);
        }catch(IOException e){
            System.out.println("Caught one io exception");
          return 1;//why i cannot use System.exit(0);
   static void copy(File src,File dest) throws IOException{
                InputStream in=new FileInputStream(src);
               OutputStream out=new FileOutputStream(dest);
              byte[] buf=new byte[1024];
              int len=0;
       while((len=in.read(buf))>0)
             out.write(buf,0,len);
     in.close();
     out.close();
    }//end_copy
// by longwen