Write preferences globally so you can read anywhere

ServiceContext serviceContext = ServiceContextFactory.getInstance(renderRequest);
PortletPreferences portletPreferences = PrefsPropsUtil.getPreferences(
serviceContext.getCompanyId());
portletPreferences.setValue("key","Value");
portletPreferences.store();

and then read like PropsUtil.get("key");

Call AUI script from a liferay ADT

<#assign aui = taglibLiferayHash["/WEB-INF/tld/aui.tld"] />


<@aui["script"]  use='aui-base'>
     var parentNode = A.one(".mainWebContentPortlet");
      parentNode.one(".navbar").setStyle('display', 'none');
   
 </@>

Reading custom attribute from hook Liferay.

Some time you want to read custom attribute from hook or from function which was called by some ajax request. You will get null value when you will try to access these attributes through expand bridge unless you set the permission first.  Some thing similar as given below

final Role adminRole = RoleLocalServiceUtil.getRole(user.getCompanyId(), "Administrator"); final List<User> adminUsers =UserLocalServiceUtil.getRoleUsers(adminRole.getRoleId()); PrincipalThreadLocal.setName(adminUsers.get(0).getUserId()); final PermissionChecker permissionChecker =PermissionCheckerFactoryUtil.create(adminUsers.get(0));

Liferay Reflection

MethodKey methodKey =
new MethodKey(ClassResolverUtil.
resolveByPortalClassLoader("com.liferay.portal.util.WebAppPool"),
"get", new Class[]{Long.class,String.class});

PortletCategory portletCategory =(PortletCategory)PortalClassInvoker.invoke(false, methodKey, new Object[] {new Long(user.getCompanyId()),"PORTLET_CATEGORY"});


For custom bean defined in a portlet

Object obj =PortletBeanLocatorUtil.locate("Injector-portlet", "your.portlets.ItemTool");
Class<?> claz = obj.getClass();
Object instance = claz.newInstance();
claz.getMethod("methodName").invoke(instance);

Liferay refresh portlet with Ajax

function refreshAssetPublisherPortlet() {
   var portletSelector = '.portlet-asset-publisher';
   var refreshInterval = 10000;   
   Liferay.Portlet.refresh(portletSelector);
   setInterval(refreshAssetPublisherPortlet, refreshInterval);
}
refreshAssetPublisherPortlet();

Calling Non-final Methods from Constructors

For more detail
http://www.informit.com/articles/article.aspx?p=20521

PDF file from Html -->ITextRenderer

If you are using ITextRenderer for pdf creation from Html, then use its method setDocumentFromString(String html) which accepts string. instead of setDocument(Document, String Uri) because SetDocument method need Document as parameter and for that you have to parse html to Document first and standard parse method from DocumentBuilder is very slow.