复制文件的异常处理
package it.com.cc.twelf;

import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class CopyFileDemo {

public static void main(String[] args) {

}
//    private static void method4()throws IOException  {
//        FileReader fr=new FileReader("fr.txt");
//        FileWriter fw=new FileWriter("fw.txt");
//        try(fr;fw){
//            char []chs=new char[1024];//            int len;//            while((len=fr.read())!=-1){//                fw.write(chs,0,len);//            }//        }catch (IOException e){//            e.printStackTrace();//        }    }

private static void method3(){
    try(FileReader fr=new FileReader("fr.txt");
        FileWriter fw=new FileWriter("fw.txt");){

        char []chs=new char[1024];
        int len;
        while((len=fr.read())!=-1){
            fw.write(chs,0,len);
        }
    }catch (IOException e){
        e.printStackTrace();
    }

}

private static void method2(){
    FileReader fr= null;
    FileWriter fw=null;
    try{
         fr=new FileReader("fr.txt");
         fw=new FileWriter("fw.txt");
        char []chs=new char[1024];
        int len;
        while((len=fr.read())!=-1){
            fw.write(chs,0,len);
        }

    }catch (IOException e){
        e.printStackTrace();
    }finally {
        if (fw!=null){
            try {
                fw.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (fr!=null){
            try {
                fr.close();
            } catch (IOException e) {
                e.printStackTrace();

            }
        }


    }


}

private static void method1()throws IOException{
    FileReader fr=new FileReader("fr.txt");
    FileWriter fw=new FileWriter("fw.txt");
    char []chs=new char[1024];
    int len;
    while((len=fr.read())!=-1){
        fw.write(chs,0,len);
    }
    fw.close();
    fr.close();
}

}