import org.jfree.data.statistics.MeanAndStandardDeviation; //导入依赖的package包/类
/**
 * Returns the mean value for an item.
 * 
 * @param rowKey the row key.
 * @param columnKey the columnKey.
 * 
 * @return The mean value.
 */
@Override
@SuppressWarnings("rawtypes")
public Number getMeanValue(final Comparable rowKey, final Comparable columnKey) {
    Number result = null;
    final MeanAndStandardDeviation masd = (MeanAndStandardDeviation) data.getObject(rowKey, columnKey);
    if (masd != null) {
        result = masd.getMean();
    }
    return result;
}
 

import org.jfree.data.statistics.MeanAndStandardDeviation; //导入依赖的package包/类
/**
 * Immutable class - should not be cloneable.
 */
public void testCloning() {
    MeanAndStandardDeviation m1 = new MeanAndStandardDeviation(1.2, 3.4);
    assertFalse(m1 instanceof Cloneable);
}