CODEWITHSUNDEEP
java
Mohit Verma
Mohit Verma

Reputation: 1

how to read particular amount of data from a file in java

I have a large file of 45MB, and suppose the memory available to me is limited and I want to read 5MB first and so on.

I need to do this using Java. Somebody please help me out.

Thanks in advance!!

Upvotes: 0

Views: 113

Answers (2)

hicksc
hicksc

Reputation: 11

I think you can just use basic byte streams for this. Check out http://docs.oracle.com/javase/tutorial/essential/io/bytestreams.html

I'd use the read(byte[] b) method of a FileInputStream class which 'Reads up to b.length bytes of data from this input stream into an array of bytes'

read(byte[] b, int off, int len) method would also allow you to do this with an offset for previously read data.

Upvotes: 1

Anshu
Anshu

Reputation: 7853

Following code would read 5000 bytes (5MB) from the file.

byte[] bytes = new byte[5000]; 
    DataInputStream dis = new DataInputStream(new FileInputStream(file)); 
      int read = 0;
      int numRead = 0;
      while (read < bytes.length && (numRead=dis.read(bytes, read, bytes.length-read)) >= 0) {
        read = read + numRead;
      }

Upvotes: 0

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