I want to check whether a List
contains an object that has a field with a certain value. Now, I could use a loop to go through and check, but I was curious if there was anything more code efficient.
Something like;
if(list.contains(new Object().setName("John"))){
//Do some stuff
}
I know the above code doesn't do anything, it's just to demonstrate roughly what I am trying to achieve.
Also, just to clarify, the reason I don't want to use a simple loop is because this code will currently go inside a loop that is inside a loop which is inside a loop. For readability I don't want to keep adding loops to these loops. So I wondered if there were any simple(ish) alternatives.
If you are using Java 8, perhaps you could try something like this:
public boolean containsName(final List<MyObject> list, final String name){
return list.stream().filter(o -> o.getName().equals(name)).findFirst().isPresent();
}
Or alternatively, you could try something like this:
public boolean containsName(final List<MyObject> list, final String name){
return list.stream().map(MyObject::getName).filter(name::equals).findFirst().isPresent();
}
This method will return true
if the List<MyObject>
contains a MyObject
with the name name
. If you want to perform an operation on each of the MyObject
s that getName().equals(name)
, then you could try something like this:
public void perform(final List<MyObject> list, final String name){
list.stream().filter(o -> o.getName().equals(name)).forEach(
o -> {
//...
}
);
}
Where o
represents a MyObject
instance.
Alternatively, as the comments suggest (Thanks MK10), you could use the Stream#anyMatch
method:
public boolean containsName(final List<MyObject> list, final String name){
return list.stream().anyMatch(o -> o.getName().equals(name));
}