How to check List <String> for null or null?

Question

It seems that I am doing, I am getting the wrong result.

My list is defined as follows:

private List<String> selectedPriorities; 

Nothing odd or fantastic on getter / setter:

 public void setSelectedPriorities(List<String> selectedPriorities) { this.selectedPriorities = selectedPriorities; } public List<String> getSelectedPriorities() { return selectedPriorities; } 

In a bean session, I want to change another List based on the content (or lack thereof) of this list.

Here is the code:

 List<String> restrictList = new ArrayList<String>(); restrictList.add("lower(logs.clazz) like lower(concat(#{logs.clazz},'%'))"); restrictList.add("lower(logs.rule) like lower(concat(#{logs.rule},'%'))"); PrioritySelectorBean selectorBean = (PrioritySelectorBean) Component.getInstance("prioritySelectorBean",true); System.out.println("constructRestrictionList selectorBean "+selectorBean.getSelectedPriorities()); if (selectorBean.getSelectedPriorities() == null) { System.out.println("IS NULL"); return restrictList; } if (selectorBean.getSelectedPriorities().isEmpty()){ System.out.println("IS EMPTY"); } if (selectorBean.getSelectedPriorities().size()<1){ System.out.println("HAS NOTHING IN IT"); return restrictList; } System.out.println("NOT NULL"); restrictList.add("lower(logs.priority) in (#{prioritySelectorBean.selectedPriorities})"); 

It always drops to NOT NULL and adds a string to limit the List. It makes me crazy! How do I discover anything on this list? Here is a snippet of the magazine

 14:24:10,057 INFO [STDOUT] constructRestrictionList selectorBean [] 14:24:10,057 INFO [STDOUT] NOT NULL 

Answer 1

You can get the result that you see if the list contains one row of zero length:

 List<String> list = new ArrayList<String>(); list.add(""); System.out.println("blah = " + list); // displays "blah = []" if (list.isEmpty()) { System.out.println("Empty"); // doesn't get displayed } 

Answer 2

perhaps because

 if (selectorBean.getSelectedPriorities().isEmpty()){ System.out.println("IS EMPTY"); } 

Need a refund?