import java.io. * ;
class RandomFileTest
... {
public static void main(String[] args) throws Exception
...{
Student s1=new Student(1,"zhangsan",98.5);
Student s2=new Student(2,"lisi",96.5);
Student s3=new Student(3,"wangwu",78.5);
RandomAccessFile raf=new RandomAccessFile("student.txt","rw");
s1.writeStudent(raf);
s2.writeStudent(raf);
s3.writeStudent(raf);
Student s=new Student();
raf.seek(0);
for(long i=0;i<raf.length();i=raf.getFilePointer())
...{
s.readStudent(raf);
System.out.println(s.num+":"+s.name+":"+s.score);
}
raf.close();
}
}
class Student
... {
int num;
String name;
double score;
public Student()
...{
}
public Student(int num,String name,double score)
...{
this.num=num;
this.name=name;
this.score=score;
}
public void writeStudent(RandomAccessFile raf) throws IOException
...{
raf.writeInt(num);
raf.writeUTF(name);
raf.writeDouble(score);
}
public void readStudent(RandomAccessFile raf) throws IOException
...{
num=raf.readInt();
name=raf.readUTF();
score=raf.readDouble();
}
}
RandomAccessFile类同时实现了DataInput和DataOutput接口，提供了对文件随机存取的功能，利用这个类可以在文件的任何位置读取或写入数据。
RandomAccessFile类提供了一个文件指针，用来标志要进行读写操作的下一数据的位置。