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justcurious
justcurious

Reputation: 845

Java - Comparing a single String value with all the String values in an ArrayList

I have an ArrayList with a set of (same) string values which I need to compare with a single String value and return true or false. Is there any way to do that in Java?

For example, say I have a <String>ArrayList with 5 values = foo, foo, foo, foo, foo (My requirement is such that all the values in the arraylist will be the SAME) and I have a String str = "foo". I need to verify that whether ALL the values in the arraylist is the SAME as the string value i.e., all the values present in the arraylist SHOULD be "foo".

I tried to google this info and all I can see is suggestions to use contains() method, in different ways, which will return true even if anyone value in the arraylist contains the specified value.

I even figured a workaround for this - Creating another arraylist with expected values and compare the two lists using equals() method and it seems to be working. I was just wondering whether there is any simple way to achieve this.

Upvotes: 2

Views: 23371

Answers (5)

Amit Bhati
Amit Bhati

Reputation: 5649

1) You can the pass the arraylist into a set.

2) Now you can get the size of set, if it is equal to 1 that means all elements are same.

3) Now you can use the contains on set to check if your value is present in it or not.

public static void main(String[] args){
          String toBeCompared="foo";
          List<String> list=new ArrayList<String>();
          list.add("foo");
          list.add("foo");
          list.add("foo");
          list.add("foo");
          list.add("foo");
          Set<String> set=new HashSet<String>(list);
          if(1==set.size()){
              System.out.println(set.contains(toBeCompared));
          }
          else{
             System.out.println("List has different values");
          }
    }

Upvotes: 3

Jordi Castilla
Jordi Castilla

Reputation: 26961

If you want to know if the array contains the string use ArrayList::contains()

String s = "HI";
ArrayList<String> strings = // here you have your string

if (string.contains(s)) {
    // do your stuff
}

If you want to check if all values are same, iterate and count. If you have JAVA8 check steffen sollution.

boolean areSame = true;
for (String str : strings) {
    if (!str.equals(s)) areSame = false;
}

if (areSame) {
    // all elements are same
}

Upvotes: 3

steffen
steffen

Reputation: 16938

That's simple with Java 8:

String str = "foo";
List<String> strings = Arrays.asList("foo", "foo", "foo", "foo", "foo");
boolean allMatch = strings.stream().allMatch(s -> s.equals(str));

For Java 7 replace the last line with:

boolean allMatch = true;
for (String string : strings) {
    if (!string.equals(str)) {
        allMatch = false;
        break;
    }
}

Upvotes: 14

JuergenKie
JuergenKie

Reputation: 109

I would do it like this:

ArrayList<String> foos = new ArrayList<>();
String str = "foo";     
for (String string : foos) {
    if(string.equals(str)){
            System.out.println("True");
    }
}

Upvotes: 1

Kore
Kore

Reputation: 436

You can use this method to do that

private boolean allAreSame(ArrayList<String> stringList, String compareTo){
    for(String s:stringList){
        if(!s.equals(compareTo))
             return false;
    }
    return true;
}

Upvotes: 2

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