Type.java

package simpledb;

import java.text.ParseException;
import java.io.*;

/**
 * Class representing a type in SimpleDB.
 * Types are static objects defined by this class; hence, the Type
 * constructor is private.
 */
public enum Type {
 INT_TYPE() {
 @Override
 public int getLen() {
 return 4;
 }

 @Override
 public Field parse(DataInputStream dis) throws ParseException {
 try {
 return new IntField(dis.readInt());
 } catch (IOException e) {
 throw new ParseException("couldn't parse", 0);
 }
 }

 }, STRING_TYPE() {
 @Override
 public int getLen() {
 return STRING_LEN+4;
 }

 @Override
 public Field parse(DataInputStream dis) throws ParseException {
 try {
 int strLen = dis.readInt();
 byte bs[] = new byte[strLen];
 dis.read(bs);
 dis.skipBytes(STRING_LEN-strLen);
 return new StringField(new String(bs), STRING_LEN);
 } catch (IOException e) {
 throw new ParseException("couldn't parse", 0);
 }
 }
 };
 
 public static final int STRING_LEN = 128;

 /**
 * @return the number of bytes required to store a field of this type.
 */
 public abstract int getLen();

 /**
 * @return a Field object of the same type as this object that has contents
 * read from the specified DataInputStream.
 * @param dis The input stream to read from
 * @throws ParseException if the data read from the input stream is not
 * of the appropriate type.
 */
 public abstract Field parse(DataInputStream dis) throws ParseException;

}