java如何在列表<Object>对象包含对象的对象上检查null?
例如:
public class HelpMetric {
private String metricId;
private String supportType;
private RequestSupportVo requestSupport;
}
public class RequestSupportVo {
private String requestSupportId;
}
public List<HelpMetric> getHelpMetric(String metricId) {
List<PolHelpMetric> list =helpMetricMapper.hlpMetricListToPolHelpMetricVoList(all);
list.forEach(x -> {
if (x.getRequestSupport() != null) {
if (x.getRequestSupport().getRequestSupportId() != null) {
}
}
}
如何使用Java8优化上述代码2 if条件null检查
如果(x.getRequestSupport()!=空){ if(x.getRequestSupport()。getRequestSupportId()!=空){
# 1 楼答案
Java的逻辑运算符与许多其他语言中的逻辑运算符一样,表现出short-circuit evaluation行为
因此,条件块如下所示:
可以安全地重写为:
由于短路行为,如果第一个条件失败,将不会评估第二个条件,并且不会有抛出
NullPointerException
的风险