性能 - 低效使用keySet迭代器而不是entrySet迭代器

Question

这段代码抛出错误 此方法使用从keySet迭代器检索的键访问Map条目的值。在map的entrySet上使用迭代器更有效，以避免Map.get（key）查找。 请指导我如何改写它

if (docPropertiesMap != null) {
        Iterator<String> properties = docPropertiesMap.keySet().iterator();
        IDocProperty[] docProperties = new IDocProperty[docPropertiesMap
                .size()];
        int iArrIndex = 0;

        while (properties.hasNext()) {
            String strPropName = properties.next();
            String[] propValue = docPropertiesMap.get(strPropName);

            IDocProperty docProperty = (IDocProperty) FDMAFactory
                    .getDataObject("DocProperty");
            docProperty.setPropertyName(strPropName);
            docProperty.setArrPropertyValues(propValue);
            docProperties[iArrIndex++] = docProperty;
        }
        metadata.setArrDocProperties(docProperties);
        return metadata;
    }

Answer 1

这是来自FindBugs的SonarQube警告。

您可以像这样重写代码：

if (docPropertiesMap != null) {
    IDocProperty[] docProperties = new IDocProperty[docPropertiesMap.size()];
    int iArrIndex = 0;

    for (Map.Entry<String, String[]> entry : docPropertiesMap.entrySet()) {
        String strPropName = entry.getKey();
        String[] propValue = entry.getValue();

        IDocProperty docProperty = (IDocProperty) FDMAFactory.getDataObject("DocProperty");
        docProperty.setPropertyName(strPropName);
        docProperty.setArrPropertyValues(propValue);
        docProperties[iArrIndex++] = docProperty;
    }
    metadata.setArrDocProperties(docProperties);
    return metadata;
}