[Java] java中的异常处理-续

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class TestIOException {
    public static void main(String[] args) throws IOException
    {
        BufferedReader br = null;
        try {
            br = new BufferedReader(new FileReader("file.txt"));
        } catch (FileNotFoundException e1) {
            e1.printStackTrace();
        }
        try{
            StringBuilder sb = new StringBuilder();
            String line = br.readLine();
            while(line!=null){
                sb.append(line);
                sb.append("\n");
                line = br.readLine();
            }
            String everything = sb.toString();
            System.out.println(everything);
        }catch(IOException e){
            e.printStackTrace();
            System.out.println("IO problem");
        }finally{
            br.close();
        }
    }
}