import com.intellij.usages.PsiElementUsageTarget; //导入依赖的package包/类
@Override
public boolean isAvailableFor(@NotNull UsageView usageView) {
  UsageTarget[] targets = ((UsageViewImpl)usageView).getTargets();
  if (targets.length == 0) return false;
  UsageTarget target = targets[0];
  if (!(target instanceof PsiElementUsageTarget)) return false;
  PsiElement element = ((PsiElementUsageTarget)target).getElement();
  if (element == null || !element.isValid()) return false;

  Project project = element.getProject();
  DataContext context = SimpleDataContext.getSimpleContext(LangDataKeys.PSI_ELEMENT.getName(), element,
                                                           SimpleDataContext.getProjectContext(project));
  HierarchyProvider provider = BrowseHierarchyActionBase.findBestHierarchyProvider(LanguageCallHierarchy.INSTANCE, element, context);
  if (provider == null) return false;
  PsiElement providerTarget = provider.getTarget(context);
  return providerTarget != null;
}
 

import com.intellij.usages.PsiElementUsageTarget; //导入依赖的package包/类
@Override
public boolean isAvailableFor(@NotNull UsageView usageView)
{
	UsageTarget[] targets = ((UsageViewImpl) usageView).getTargets();
	if(targets.length == 0)
	{
		return false;
	}
	UsageTarget target = targets[0];
	if(!(target instanceof PsiElementUsageTarget))
	{
		return false;
	}
	PsiElement element = ((PsiElementUsageTarget) target).getElement();
	if(element == null || !element.isValid())
	{
		return false;
	}
	if(!(element instanceof PsiVariable))
	{
		return false;
	}
	PsiFile file = element.getContainingFile();
	return file instanceof PsiJavaFile;
}
 

import com.intellij.usages.PsiElementUsageTarget; //导入依赖的package包/类
private static boolean qualifiesToTargetClasses(@NotNull PsiJavaCodeReferenceElement qualifier, @NotNull UsageTarget[] targets) {
  for (UsageTarget target : targets) {
    if (target instanceof PsiElementUsageTarget) {
      PsiElement element = ((PsiElementUsageTarget)target).getElement();
      if (element instanceof PsiClass) {
        if (Comparing.equal(qualifier.getReferenceName(), target.getName())) {
          return true;
        }
      }
    }
  }
  return false;
}
 

import com.intellij.usages.PsiElementUsageTarget; //导入依赖的package包/类
@Override
public boolean isAvailableFor(@NotNull UsageView usageView) {
  UsageTarget[] targets = ((UsageViewImpl)usageView).getTargets();
  if (targets.length == 0) return false;
  UsageTarget target = targets[0];
  if (!(target instanceof PsiElementUsageTarget)) return false;
  PsiElement element = ((PsiElementUsageTarget)target).getElement();
  if (element == null || !element.isValid()) return false;
  if (!(element instanceof PsiVariable)) return false;
  PsiFile file = element.getContainingFile();
  return file instanceof PsiJavaFile;
}