Java 8如何使用lambda表达式简化for循环
我的代码中有这个方法,需要使用Java8表达式简化和减少行。 Lambda可以用于此目的,但如果没有列表作为输入,它似乎是不可能的Java 8如何使用lambda表达式简化for循环,java,for-loop,lambda,foreach,java-8,Java,For Loop,Lambda,Foreach,Java 8,我的代码中有这个方法,需要使用Java8表达式简化和减少行。 Lambda可以用于此目的,但如果没有列表作为输入,它似乎是不可能的 public ResourceUsage[] filterResourceUsages(ResourceUsage[] resourceUsages, int role, int includeResourceType) throws SpiderException { ArrayList<ResourceUsage> filte
public ResourceUsage[] filterResourceUsages(ResourceUsage[] resourceUsages, int role, int includeResourceType)
throws SpiderException
{
ArrayList<ResourceUsage> filteredResourceUsages = new ArrayList<>();
String[] ids = new String[resourceUsages.length];
for (int i = 0; i < resourceUsages.length; i++)
{
ids[i] = resourceUsages[i].resource;
}
ResourceData[] resourceData = resourceToolkitAdapter.getData(ids);
for (int i = 0; i < resourceData.length; i++)
{
if (resourceUsages[i].role == role && resourceData[i].basic.type == includeResourceType)
{
filteredResourceUsages.add(resourceUsages[i]);
}
}
return filteredResourceUsages.toArray(new ResourceUsage[filteredResourceUsages.size()]);
}
public ResourceUsage[]FilterResourceSages(ResourceUsage[]resourceUsages,int角色,int includeResourceType)
抛出SpiderException
{
ArrayList filteredResourceUsages=新建ArrayList();
String[]ids=新字符串[resourceUsages.length];
for(int i=0;i
我试过使用resourceUsages.forEach(resourceUsages.resource->do something)代码>但是没有列表作为输入似乎是不可能的
有没有办法简化此代码?最好使用列表而不是数组
我还将假装可以依次调用每个资源上的resourceToolkitAdapter.getData()
,而不是批量调用
结果会是这样:
public List filterResourceSages(列表资源使用、int角色、int includeResourceType)
抛出SpiderException
{
返回resourceUsages.stream()
.filter(r->r.role==角色)
.filter(r->resourceToolkitAdapter.getData(r.resource).basic.type==includeResourceType)
.collect(Collectors.toList());
}
您可以使用数组执行此操作
Arrays.stream(resourceUsages)
.forEach(e->System.out.print(e));
以下是原始阵列和批处理解决方案:
public ResourceUsage[] filterResourceUsages(ResourceUsage[] resourceUsages, int role, int includeResourceType)
throws SpiderException {
String[] ids = Stream.of(resourceUsages)
.map(ResourceUsage::getResource)
.toArray(String[]::new);
Map<String, ResourceData> resourceDataMap = Stream.of(resourceToolkitAdapter.getData(ids))
.collect(Collectors.toMap(ResourceData::id, Function.identity()));
return Stream.of(resourceUsages)
.filter(usage -> usage.role == usage)
.filter(resourceDataMap::containsKey)
.filter(usage -> resourceDataMap.get(usage.resource).basic.type == includeResourceType)
.toArray(ResourceUsage[]::new);
}
public ResourceUsage[]FilterResourceSages(ResourceUsage[]resourceUsages,int角色,int includeResourceType)
抛出SpiderException{
String[]ids=Stream.of(resourceUsages)
.map(ResourceUsage::getResource)
.toArray(字符串[]::新建);
Map resourceDataMap=Stream.of(resourceToolkitAdapter.getData(ids))
.collect(Collectors.toMap(ResourceData::id,Function.identity());
返回流。of(资源使用)
.filter(用法->用法.role==用法)
.filter(resourceDataMap::containsKey)
.filter(用法->resourceDataMap.get(用法.resource).basic.type==includeResourceType)
.toArray(ResourceUsage[]::新建);
}
与Matthew的答案相反,我假设应使用一批ID调用resourceToolkitAdapter.getData()
public ResourceUsage[]FilterResourceSages(ResourceUsage[]resourceUsages,int角色,int includeResourceType)
抛出SpiderException
{
ResourceData[]ResourceData=resourceToolkitAdapter.getData(
Arrays.stream(resourceUsages)
.map(r->r.resource)
.toArray(字符串[]::新建)
);
返回IntStream
.range(0,resourceData.length)
.filter(i->resourceUsages[i]。角色==角色)
.filter(i->resourceData[i].basic.type==includeResourceType)
.mapToObj(i->resourceUsages[i])
.toArray(ResourceUsage[]::新建);
}
“如果没有列表作为输入,似乎不可能”Arrays.stream(myArray)
final List id=resourceUsages.stream().map(e->e.resource.collect(toList());