66 lines
1.5 KiB
Java
66 lines
1.5 KiB
Java
// iostreams/UsingRandomAccessFile.java
|
|
// (c)2020 MindView LLC: see Copyright.txt
|
|
// We make no guarantees that this code is fit for any purpose.
|
|
// Visit http://OnJava8.com for more book information.
|
|
import java.io.*;
|
|
|
|
public class UsingRandomAccessFile {
|
|
static String file = "rtest.dat";
|
|
public static void display() {
|
|
try(
|
|
RandomAccessFile rf =
|
|
new RandomAccessFile(file, "r")
|
|
) {
|
|
for(int i = 0; i < 7; i++)
|
|
System.out.println(
|
|
"Value " + i + ": " + rf.readDouble());
|
|
System.out.println(rf.readUTF());
|
|
} catch(IOException e) {
|
|
throw new RuntimeException(e);
|
|
}
|
|
}
|
|
public static void main(String[] args) {
|
|
try(
|
|
RandomAccessFile rf =
|
|
new RandomAccessFile(file, "rw")
|
|
) {
|
|
for(int i = 0; i < 7; i++)
|
|
rf.writeDouble(i*1.414);
|
|
rf.writeUTF("The end of the file");
|
|
rf.close();
|
|
display();
|
|
} catch(IOException e) {
|
|
throw new RuntimeException(e);
|
|
}
|
|
try(
|
|
RandomAccessFile rf =
|
|
new RandomAccessFile(file, "rw")
|
|
) {
|
|
rf.seek(5*8);
|
|
rf.writeDouble(47.0001);
|
|
rf.close();
|
|
display();
|
|
} catch(IOException e) {
|
|
throw new RuntimeException(e);
|
|
}
|
|
}
|
|
}
|
|
/* Output:
|
|
Value 0: 0.0
|
|
Value 1: 1.414
|
|
Value 2: 2.828
|
|
Value 3: 4.242
|
|
Value 4: 5.656
|
|
Value 5: 7.069999999999999
|
|
Value 6: 8.484
|
|
The end of the file
|
|
Value 0: 0.0
|
|
Value 1: 1.414
|
|
Value 2: 2.828
|
|
Value 3: 4.242
|
|
Value 4: 5.656
|
|
Value 5: 47.0001
|
|
Value 6: 8.484
|
|
The end of the file
|
|
*/
|