Java Tutorial/File/ByteOrder

Get default byte ordering

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
public class Main {
  public static void main(String[] argv) throws Exception {
    ByteBuffer buf = ByteBuffer.allocate(10);
    
    ByteOrder order = buf.order(); // ByteOrder.BIG_ENDIAN
  }
}

Set to little endian

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
public class Main {
  public static void main(String[] argv) throws Exception {
    ByteBuffer buf = ByteBuffer.allocate(10);
    buf.order(ByteOrder.LITTLE_ENDIAN);
  }
}