sort array of objects by surname java

Question

I am stuck on this following piece of code I have been trying to use a bubble sort to sort the array of objects by surname then print it out. where Am i going wrong and how can i print it out? here is my code

for(int i = 1; i < clipArray.length; i++) {
    for(int j = 0; j < clipArray.length; j++) {
        if(((clipArray[j].getSurname()).compareToIgnoreCase((clipArray[j+1].getSurname()))) {
            Clip temp = clipArray[j];
            clipArray[j] = clipArray[j+1];
            clipArray[j+1] = temp;
        }
    }
}

problem: required boolean, found int

First problem I see is that clipArray[j+1] will index out of the array (see your second loop) — dcp
– dcp, Commented Oct 24, 2013 at 14:56
Tell us what's going wrong first. Provide some input and output. SO is not for code dumps. Please describe your problem, steps you've taken to try solving it, etc. — Dave Newton
– Dave Newton, Commented Oct 24, 2013 at 14:56
That's because compareToIgnoreCase returns an int. You need to compare this result with another integer like < 0. — Luiggi Mendoza
– Luiggi Mendoza, Commented Oct 24, 2013 at 14:58

Community · Accepted Answer · 2020-06-20 09:12:55Z

2

The problem is that String#compareToIgnoreCase returns an int and you require a boolean result for if statement. From its javadoc:

Returns

a negative integer, zero, or a positive integer as the specified String is greater than, equal to, or less than this String, ignoring case considerations

So, compare the result of this method with another number according to the definition.

if (clipArray[j].getSurname().compareToIgnoreCase(clipArray[j+1].getSurname()) < 0) {
    //...
}

Also, you have another error in your for loop declarations. They should be like this:

for(int i = 1; i < clipArray.length; i++) {
    for(int j = 0; j < clipArray.length - 1; j++) { //spot the difference
        //...
    }
}

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Oct 24, 2013 at 15:02

Luiggi Mendoza

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3 Comments

user2914851 Over a year ago

thank you very much i understand now! last problem i'm having is that I can't print the sorted array

user2914851 Over a year ago

System.out.println(clipArray[].getSurname());

But I'm Not A Wrapper Class Over a year ago

After you are done sorting the array, create a new loop and print out each surname.

Prabhakaran Ramaswamy · Accepted Answer · 2013-10-24 14:56:52Z

2

Your Comparator class

class SampleComparator implements Comparator<Clip> {
    @Override
    public int compare(Clip o1, Clip o2) {

           return o1.getSurname().compareToIgnoreCase(o2.getSurname());
   }
}

Your sorting here

Arrays.sort(clipArray,new SampleComparator());

answered Oct 24, 2013 at 14:56

Prabhakaran Ramaswamy

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2 Comments

Luiggi Mendoza Over a year ago

-1: This is a homework exercise. Using Arrays#sort is obviously not an answer.

But I'm Not A Wrapper Class Over a year ago

This isn't the issue. Why are people up-voting this?

Bharath R · Accepted Answer · 2013-10-24 15:00:50Z

2

The error is because

compareToIgnoreCase return int values not boolean.

returns a negative integer, zero, or a positive integer as the specified String is greater than, equal to, or less than this String, ignoring case considerations.

If only takes boolean.

answered Oct 24, 2013 at 15:00

Bharath R

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1 Comment

user2914851 Over a year ago

so how can i fix it so that it is comparing the strings and i can then sort it alphabetically?

npst · Accepted Answer · 2013-10-24 15:02:27Z

0

I assume your clipArray is filled with objects that support the getSurname()-method.

The method compareToIgnoreCase returns an int, so you should compare it with a value in your if-statement, like

if(foo.compareTo(bar) > 0)

answered Oct 24, 2013 at 15:02

npst

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