ArrayList filter

Question

How can you filter out something from a Java ArrayList like if you have    How are you How you doing Joe Mike   And the filter is  How  it will remove Joe and Mike

User · Answer

write your self a filter function   public List lt T gt  filter Predicate lt T gt  criteria  List lt T gt  list            return list stream   filter criteria  collect Collectors  lt T gt toList          And then use      list   new Test   filter x - gt  x  gt  2  list     This is the most neat version in Java  but needs JDK 1 8 to support lambda calculus

User · Answer

I agree with a previous answer that Google Guava is probably helping a lot here  readability-wise   final Iterables removeIf list  new Predicate lt String gt           Override     public boolean apply String input            if input contains  How        or more complex pattern matching             return true                    return false               Please note that this is basically a duplicate of Guava - How to remove from a list  based on a predicate  keeping track of what was removed

User · Answer

Probably the best way is to use Guava List lt String gt  list   new ArrayList lt String gt     list add  quot How are you quot    list add  quot How you doing quot    list add  quot Joe quot    list add  quot Mike quot         Collection lt String gt  filtered   Collections2 filter list      Predicates containsPattern  quot How quot     print filtered    prints How are you How you doing  In case you want to get the filtered collection as a list  you can use this  also from Guava   List lt String gt  filteredList   Lists newArrayList Collections2 filter      list  Predicates containsPattern  quot How quot

User · Answer

As you didn t give us very much information  I m assuming the language you re writing the code in is C   First of all  Prefer System Collections Generic List over an ArrayList  Secondly  One way would be to loop through every item in the list and check whether it contains  How   Another way would be to use LINQ  Here s a quick example that filters out every item which doesn t contain  How    var list   new List lt string gt     list AddRange new string          How are you         How you doing         Joe        Mike        foreach  string str in list Where s   gt  s Contains  How           Console WriteLine str     Console ReadLine

User · Answer

Iterate through the list and check if contains your string  How  and if it does then remove  You can use following code      need to construct a new ArrayList otherwise remove operation will not be supported List lt String gt  list   new ArrayList lt String gt  Arrays asList new String                                        How are you     How you doing    Joe    Mike      System out println  List Before      list   for  Iterator lt String gt  it list iterator    it hasNext           if   it next   contains  How            it remove       NOTE  Iterator s remove method  not ArrayList s  is used    System out println  List After      list     OUTPUT   List Before   How are you   How you doing   Joe  Mike  List After   How are you   How you doing

User · Answer

In java-8  they introduced the method removeIf which takes a Predicate as parameter   So it will be easy as   List lt String gt  list   new ArrayList lt  gt  Arrays asList  How are you                                                      How you doing                                                      Joe                                                      Mike     list removeIf s - gt   s contains  How

[java] ArrayList filter

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