CODEWITHSUNDEEP
java
Hector Barbossa
Hector Barbossa

Reputation: 5528

Search array of java custom objects

I have an array of custom objects CustomClass[] customArr where CustomClass is like

Class CustomClass{

private String key;
private String value;

//getter & setters

}

Now I want to search this array by a particular value.What is the best way to do this ?

Upvotes: 1

Views: 508

Answers (2)

Adam Zalcman
Adam Zalcman

Reputation: 27233

Implement equals(). Make sure you comply with the contract of the method.

Also, if you search often and the array is large you probably want to consider a better data structure for this, e.g. one of the implementations of Set if you're interested in the presence of particular instances within the data structure or one of the implementations of Map if you want to search by a key. See java.util for details.

Note that some of the data structures in java.util may require you to provide your own version of hashCode() (e.g. HashSet) and some may require you to implement Comparable interface or provide a Comparator (e.g. TreeSet).

If you provide your own version of hashCode() make sure it is consistent with your equals() (see the javadoc for equals()).

If you really must use an array, then consider one of the versions of Arrays.binarySearch(). Note that you can only use it on sorted arrays.

Upvotes: 5

The Real Baumann
The Real Baumann

Reputation: 1961

Implement Comparable. Then you can use java.util.Arrays to search and sort your array.

Class CustomClass implements Comparable {

private String key;
private String value;

//getter & setters 

public int compareTo(Object other){
     if( other instanceOf CustomClass )
     {
         CustomClass otherCustomClass = (CustomClass) other;
         int val = this.key.compareTo( otherCustomClass.key  );
         if( key != 0 ) return key;
         return this.value.compareTo( otherCustomClass.value );
     }
     return -1;
}

}

Upvotes: 0

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