how to check if all elements of java collection match some condition?

问题

I have an ArrayList<Integer>. I want to check if all elements of the list are greater then or less then certain condition. I can do it by iterating on each element. But I want to know if there is any method in Collection class to get the answer like we can do to find maximum or minimum with Collections.max() and Collections.min() respectively.

回答1:

If you have java 8, use stream's allMatch function (reference):

 ArrayList<Integer> col = ...;
 col.stream().allMatch(i -> i>0); //for example all integers bigger than zero

回答2:

You can use Google guavas Iterables.all

 Iterables.all(collection, new Predicate() {
    boolean apply(T element)  {
       .... //check your condition 
   } 
 } 

回答3:

You cannot check values without iterating on all elements of the list.

for(Integer value : myArrayList){

    if(value > MY_MIN_VALUE){
        // do my job
    }
}

I hope this will help

来源：https://stackoverflow.com/questions/24304129/how-to-check-if-all-elements-of-java-collection-match-some-condition