AbstractNMEASentence.java

package com.buglabs.nmea2;

import com.buglabs.nmea.sentences.NMEAParserException;

/**
 * Base class of all NMEA sentences
 * 
 * @author kgilmer
 * 
 */
public abstract class AbstractNMEASentence {
	private String FIELD_SEPARATOR = ",";
	private String CHECKSUM_SEPARATOR = "*";
	protected String checksum = null;
	private String name = null;

	public AbstractNMEASentence(String sentence) {
		initialize();
		String[] fields = parseChecksum(sentence).split(FIELD_SEPARATOR);
		name = fields[0];

		for (int i = 1; i < fields.length; ++i) {
			if (isEmpty(fields[i])) {
				//Ignore empty values.
				continue;
			}

			try {
				parseField(i, fields[i], fields);
			} catch (RuntimeException e) {
				throw new NMEAParserException(e.getMessage());
			}
		}

		validate();
	}

	/**
	 * Initialize any member objects here.
	 */
	protected void initialize() {

	}

	private String parseChecksum(String sentence) {
		String[] splitSentence = sentence.split("\\" + CHECKSUM_SEPARATOR);

		if (splitSentence.length > 1) {
			checksum = splitSentence[1];
		}

		return splitSentence[0];
	}

	/**
	 * @param sentence
	 */
	protected abstract void parseField(int index, String value, String[] fields);

	/**
	 * Invalid sentences should throw NMEAParserException
	 */
	protected abstract void validate();

	/**
	 * @param val
	 * @return
	 */
	protected boolean isEmpty(String val) {
		return val == null || val.length() == 0;
	}

	/**
	 * @return Sentence Checksum
	 */
	public String getChecksum() {
		return checksum;
	}

	/**
	 * @return Sentence name
	 */
	public String getName() {
		return name;
	}
}