CODEWITHSUNDEEP
javaarrayslistcomparisoniteration
crmepham
crmepham

Reputation: 4760

How do I build and compare an Array against another array?

I have an ArrayList containing strings retrieved from a database. The strings are tags for individual posts of a blog, for example:

video, java, php, xml,

css, java, foo, bar, 

xml, php, foo, bar, dog

I am attempting to loop through the list. Split each string by their commas into an array and check if my uniqueTag array doesn't contain an element from the split array. If it doesn't, add it to the uniqueTag array.

This is how far I've got:

List<String> tagList = conn.getAllTags();
String[] uniqueTags;
for(String item: tagList){
    // split the row into array of comman seperated elements
    String[] splitItem = item.split(",");

    for(int i=-1; i<=splitItem.length; i++){
        // compare this element with elements in uniqueTags
        // and if it doesn't exit in uniqueTags
        // add it.
    }
}

How do I compare and dynamically build the uniqueTags array?

Upvotes: 0

Views: 77

Answers (3)

Raj
Raj

Reputation: 942

Why do not you try something like this.

Create a List<String> splitIteams of split items and do 

List<String> distinct = splitItems.stream().distinct().collect(Collectors.toList());
System.out.printf("Split Items : %s,  Distinct list : %s ", splitItems, distinct);

Edit - deleted one extra %s

Upvotes: 1

Wilson
Wilson

Reputation: 176

public static void compareArrays(int[] array1, int[] array2) {
    boolean b = true;
    if (array1 != null && array2 != null){

      if (array1.length != array2.length)
          b = false;
      else
          for (int i = 0; i < array2.length; i++) {
              if (array2[i] != array1[i]) {
                  b = false;    
              }                 
        }
    }else{
      b = false;
    }
    System.out.println(b);
}

Upvotes: 0

Mena
Mena

Reputation: 48434

I would use a Set<String> to prevent duplicate values.

Something along the lines of:

Set<String> uniques = new HashSet<String>();
for(String item: tagList){
    // split the row into array of comman seperated elements
    String[] splitItem = item.split(",");
    for (String item: splitItem) {
        uniques.add(item.trim()); // trimming whitespace and adding to set

...

Upvotes: 3

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