Print when espression - check if is empty array [duplicate] - java

This question already has answers here:
how to check for an empty array java [duplicate]
(6 answers)
Closed 4 years ago.
In JasperReport I want to print a field when it does not contain empty array.
How can I check it?
In "Print when expression" it is possible to write:
$F{myField} != null
but as $F{myField} is an empty array (so it is not null) it does not work.
Is there any method to check it? It seems to me that there is no isEmpty() function for JasperReport.


Try write something like:
$F{myField}.length() == 0

Related

Check date for null [duplicate]

This question already has answers here:
Best way to check for null values in Java?
(19 answers)
Closed 3 years ago.
I want to check if date from database is empty like this:
private boolean hasAccountExpired(LocalDateTime password_changed_at) {
return password_changed_at.isEqual(null);
}
But I get NPE. What is the proper way to check if date field from database is empty?

password_changed_at == null will tell you if it's null.
However, this doesn't necessarily tell you if it's empty in the database - that depends on your implementation.

java - How do I remove an object from an ArrayList if a condition is met? [duplicate]

This question already has answers here:
Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop
(31 answers)
ArrayList filter [duplicate]
(6 answers)
Closed 5 years ago.
I want to remove some objects (if they meet a condition) of an ArrayList while looping through it. But that will obviously throw a 'ConcurrentModificationException'.
So, what's the best way of doing this?
edit: My condition is a number comparision, so if an objects' variable is greater than a value, the object must be removed from the list..

In Java 8:
rooms.removeIf(r -> r.getSize() >= 40) ;

Simple check operation is not working in java [duplicate]

This question already has answers here:
How do I compare strings in Java?
(23 answers)
Closed 7 years ago.
String TypedMaxNumber = MaxValue.getText();
if(TypedMaxNumber == "100")
System.out.println(TypedMaxNumber+" = 100");
I think it is a silly problem, but when I am running to run this program and I type 100 in the text Field it is not going inside the loop. What could be the reason.

I am running to run this program and I type 100 in the text Field it
is not going inside the loop.
Its
if(TypedMaxNumber.equals("100"))
Since TypedMaxNumber is of type String. equals() check for value equality

How to assign a List<List<String>> variable to a empty list in java? [duplicate]

This question already has answers here:
Collections.emptyList() vs. new instance
(7 answers)
Closed 7 years ago.
I have a line of code
List<List<String>> get_valuesofValues = new ArrayList<List<String>>((Collection<? extends List<String>>)map.get(value_atIndex));
"get_valuesofValues" will be null in some places. How can I assign it to a empty list in order to avoid exception?
Should be something like this :
if(get_valuesofValues == null){
get_valuesofValues =((Collection.<List<String>>)emptyList();
}

Use Collections.emptyList() method. Please note, that such collections cannot be modified (add/replace/remove of elements produces an exception).

Array is initializing more elements than told too [duplicate]

This question already has answers here:
Java arrays printing out weird numbers and text [duplicate]
(10 answers)
Closed 8 years ago.
Java:
int [] list = new int [7];
System.out.print(list);
In the console it prints: [I#1f96302
Not only is it giving values other than ints, but it is giving more than I asked it too.

[l#1f96302 is the default way an Object is printed (that's what Object's toString() method returns for arrays). Try System.out.print(Arrays.toString(list)) instead, which will display the elements of the array.

Categories