The two classes are similar,who can help me to reduce the duplicate code

Question

/./DoubleFilter Class
public class DoubleFilter {
    private Vector data = null;
    private String symbol = null;
    private Vector filterData = null;
    public DoubleFilter(Vector _data, String _symbol) {
        data = _data;
        symbol = _symbol;
        filterData = new Vector();
    public Vector filter(Double _value){
        if(_value==null){
            return null;
        if(symbol.equals(Symbol.LESS)){
            return less(_value);
        }else if(symbol.equals(Symbol.GREATER)){
            return greater(_value);
        }else if(symbol.equals(Symbol.EQUAL)){
            return equals(_value);
        }else if(symbol.equals(Symbol.NOT_EQUAL)){
            return notEquals(_value);
        }else if(symbol.equals(Symbol.NOT_LESS)){
            return notLess(_value);
        }else if(symbol.equals(Symbol.NOT_GREATER)){
            return notGreater(_value);
        }else{
            return null;
    private Vector less(Double _value) {
        for (int i = 0; i < data.size(); i++) {
            Double baseValue = (Double) data.get(i);
            if (baseValue.compareTo(_value) < 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector greater(Double _value) {
        for (int i = 0; i < data.size(); i++) {
            Double baseValue = (Double) data.get(i);
            if (baseValue.compareTo(_value) > 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector equals(Double _value) {
        for (int i = 0; i < data.size(); i++) {
            Double baseValue = (Double) data.get(i);
            if (baseValue.compareTo(_value) == 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector notLess(Double _value) {
        for (int i = 0; i < data.size(); i++) {
            Double baseValue = (Double) data.get(i);
            if (baseValue.compareTo(_value) <= 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector notGreater(Double _value) {
        for (int i = 0; i < data.size(); i++) {
            Double baseValue = (Double) data.get(i);
            if (baseValue.compareTo(_value) >= 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector notEquals(Double _value) {
        for (int i = 0; i < data.size(); i++) {
            Double baseValue = (Double) data.get(i);
            if (baseValue.compareTo(_value) > 0
                    || baseValue.compareTo(_value) < 0) {
                filterData.add(data.get(i));
        return filterData;
//IntegerFilter Class
public class IntegerFilter {
    private Vector data = null;
    private String symbol = null;
    private Vector filterData = null;
    public IntegerFilter(Vector _data, String _symbol) {
        data = _data;
        symbol = _symbol;
        filterData = new Vector();
    public Vector filter(Integer _value) {
        if (_value == null) {
            return null;
        if (symbol.equals(Symbol.LESS)) {
            return less(_value);
        } else if (symbol.equals(Symbol.GREATER)) {
            return greater(_value);
        } else if (symbol.equals(Symbol.EQUAL)) {
            return equals(_value);
        } else if (symbol.equals(Symbol.NOT_EQUAL)) {
            return notEquals(_value);
        } else if (symbol.equals(Symbol.NOT_LESS)) {
            return notLess(_value);
        } else if (symbol.equals(Symbol.NOT_GREATER)) {
            return notGreater(_value);
        } else {
            return null;
    private Vector less(Integer _value) {
        for (int i = 0; i < data.size(); i++) {
            Integer baseValue = (Integer) data.get(i);
            if (baseValue.compareTo(_value) < 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector greater(Integer _value) {
        for (int i = 0; i < data.size(); i++) {
            Integer baseValue = (Integer) data.get(i);
            if (baseValue.compareTo(_value) > 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector equals(Integer _value) {
        for (int i = 0; i < data.size(); i++) {
            Integer baseValue = (Integer) data.get(i);
            if (baseValue.compareTo(_value) == 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector notLess(Integer _value) {
        for (int i = 0; i < data.size(); i++) {
            Integer baseValue = (Integer) data.get(i);
            if (baseValue.compareTo(_value) <= 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector notGreater(Integer _value) {
        for (int i = 0; i < data.size(); i++) {
            Integer baseValue = (Integer) data.get(i);
            if (baseValue.compareTo(_value) >= 0) {
                filterData.add(data.get(i));
        return filterData;
    private Vector notEquals(Integer _value) {
        for (int i = 0; i < data.size(); i++) {
            Integer baseValue = (Integer) data.get(i);
            if (baseValue.compareTo(_value) > 0
                    || baseValue.compareTo(_value) < 0) {
                filterData.add(data.get(i));
        return filterData;
}

Answer 1

additionally I'd remove all but one of the for-loops and call a filter() method on a Filter object that chooses wether to select this item or not
public interface Filter {
  public boolean select(Object o);
public abstract class ComparableFilter {
  private Comparable base;
  public ComparableFilter(Comparable base) {
    this.base=base;
public class EqualComparableFilter {
  public EqualComparableFilter(Comparable base) {
    super(base);
  public boolean select(Object o) {
    return base.compareTo(o) == 0;
}