NullableKeyWrapper.java

package org.karmaexchange.dao;

import javax.annotation.Nullable;
import javax.xml.bind.annotation.XmlTransient;

import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.NoArgsConstructor;
import lombok.ToString;

import com.googlecode.objectify.Key;

@Data
@NoArgsConstructor
@EqualsAndHashCode(callSuper=true)
@ToString(callSuper=true)
public class NullableKeyWrapper<T> extends KeyWrapper<T> {

  public static <T> NullableKeyWrapper<T> create() {
    return new NullableKeyWrapper<T>(null);
  }

  public static <T> NullableKeyWrapper<T> create(Key<T> key) {
    return new NullableKeyWrapper<T>(key);
  }

  protected NullableKeyWrapper(@Nullable Key<T> key) {
    this.key = key;
  }

  public void setKey(@Nullable String keyStr) {
    if (keyStr == null) {
      key = null;
    } else {
      key = Key.<T>create(keyStr);
    }
  }

  @Override
  public String getKey() {
    return (key == null) ? null : key.getString();
  }

  @XmlTransient
  public boolean isNull() {
    return (key == null);
  }

  @Override
  public int compareTo(KeyWrapper<T> other) {
    if (key == other.key) {
      return 0;
    }
    if (key == null) {
      return -1;
    }
    return this.key.compareTo(other.key);
  }
}