下面是一个小程序,但运行总是有异常,不能显示读取的文件! 本人新手,谢谢指教!
import java.io.*;
public class TestFileInputStream {
public static void main(String[] args) {
FileInputStream in = null;
int b = 0;
try {
new FileInputStream("E:\\all java\\MyFirstTest\\src\\HelloWorld.java");
System.out.println("ok!");
} catch (FileNotFoundException e) {
System.out.println("找不到文件");
System.exit(-1);
e.printStackTrace();
}
try{
long num = 0;
[color=red]while((b = in.read())!=-1){[/color]
System.out.print((char)b);
num++;
b = in.read();
}
in.close();
System.out.println();
System.out.println("共读取字节数"+num);
}catch(IOException e){
System.out.println("文件读取错误");
System.exit(-1);
}catch(NullPointerException npe){
System.out.println("空指针错误");
npe.printStackTrace();
}
}
}
结果:
ok!
空指针错误
java.lang.NullPointerException
at TestFileInputStream.main(TestFileInputStream.java:20)