Linear array search

Question

I'm pretty new to java and I'm trying to learn so I'm just wondering how I could preform a linear search through my array. This is what I've done so far but it doesn't work.

public boolean contains(Object elem)
    {
        boolean result = false;
        for(int i=0;i<this.vector.length;i++)
            if(elem.equals(this.vector[i]))
                result=true;
            else
                result=false;
        return result;
    }

    public int indexOf(V elem)
    {
        int pos = 0;
        for(int i=0;i<this.vector.length;i++)
            if(this.vector[i].equals(elem))
                pos=i;
            else
                pos= -1;
        return pos;
    }

Can you show us how it fails? An example, maybe.

dfb
– dfb

2011-05-19 16:37:30 +00:00
Commented May 19, 2011 at 16:37 — dfb
– dfb, Commented May 19, 2011 at 16:37

Chris Morgan · Accepted Answer · 2011-05-19 16:38:28Z

3

Your contains() function only returns true if the passed elem is the last item in the array. If you find it, you should return true immediately.

Your indexOf() method suffers from the same issue.

answered May 19, 2011 at 16:38

Chris Morgan

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1 Comment

Marcelo Over a year ago

@ogward Accepting the answer would be very nice ;)

Lirm · Accepted Answer · 2011-05-19 16:36:49Z

1

You're missing a break after you've found the element.

answered May 19, 2011 at 16:36

Lirm

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Comments

xmedeko · Accepted Answer · 2012-07-24 08:15:39Z

1

Oneliner:

Arrays.asList(vector).indexOf(elem);

It just creates and deletes one more object (ArrayList) in the memory. Should not be a problem in the most of situations.

answered Jul 24, 2012 at 8:15

xmedeko

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Comments

Olaf · Accepted Answer · 2011-05-19 16:37:14Z

0

You need to break your loop when you find your match.

answered May 19, 2011 at 16:37

Olaf

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Comments

Dirk · Accepted Answer · 2011-05-19 16:38:40Z

0

There are a few problems with that code: in both methods, you always search through the entire array, even if you have found the element already. In both methods, this is the source of a bug (and less importantly: it is not as efficient as it could be).

for(int i=0;i<this.vector.length;i++)
    if(elem.equals(this.vector[i]))
       return true;
return false;

(and similar for the other method) might be a better implementation.

answered May 19, 2011 at 16:38

Dirk

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