insertion sort for an object-array?

Question

For instance, I have the following classes:

public class FooService {

    private String name;
    private int quantity;

    public FooService(String name, int quantity) {
        this.name = name;
        this.quantity = quantity;
    }
    // getters + setters
}

and

public class FooStorage {

    private FooService [] services = new FooService[10];

    public void add(FooService fooService) {

    }
}

I want to sort the services array in an alphabetical order according to each element's name parameter.

I know I can use a comparator in this case but it is very expensive when importing large amount of data. Can anyone help me with the insertion sort here?

EDIT: I am not allowed to use Collections. Also, do not mind about the fixed size of the array. I am allocating initially 5000 slots and then multiplying by 2 if the 5000th slot is reached in my program.

Jakkra · Accepted Answer · 2014-05-01 13:22:33Z

3

Make FooService implement Comparable. Make the compareTo method compare by alphabetic order. And then use Arrays.sort(services); it will sort your array.

Read more here: http://docs.oracle.com/javase/6/docs/api/java/util/Arrays.html#sort(java.lang.Object[])

answered May 1, 2014 at 13:22

Jakkra

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stridecolossus · Accepted Answer · 2014-05-01 13:29:08Z

2

If you are periodically adding lots of new items into your array then the Arrays.sort() approach described by @Jakkra is a sound approach.

If you're frequently only adding a few items each time then this approach is a bit heavy-weight, you might want to consider a TreeSet (also requires implementing Comparable).

EDIT: Just seen your update saying you cannot use collections (!), so the second option is no good to you but I'll leave it here for posterity.

answered May 1, 2014 at 13:29

stridecolossus

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Sufian · Accepted Answer · 2016-07-13 14:18:17Z

0

If you are really keen on insertion sort try this..

public void sort(){
    for(int i=2;i<services.length;i++){
        int j=i-1;
        FooService key=services[i];
        while((j>-1)&& ((services[j].getName().compareTo(key.getName()))>0)){
            services[j+1]=services[j];
            j--;
        }
        services[j+1]=key;
    }
}

P.S. You ain't using collections... compareTo() is just helping you on string comparisons, to implement your own string comparisons will be reinventing the wheel.

edited Jul 13, 2016 at 14:18

Sufian

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answered May 1, 2014 at 14:05

SandeepGodara

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1 Comment

Bravo Over a year ago

btw, why did you assign i as 2 in the first for loop? Thanks in advance

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