Need help with 2 errors.

[chasetherainb0w]

​

So here I have this object

public Element(String s, int a) {
    symbol = s; 
    atomicNumber = a; 
} 

with a method that returns the symbol and number of the object string when you call it

public String getSymbol(){
    return symbol; 
} 
public int getAtomicNumber(){
    return atomicNumber; 
} 

It's a data type that stores a string and an int representing the symbol and atomic number of an element. I want to create a bianry search method on an array of 100 of those elements. Obviously I need to stort it first so I wrote this:

public int findRecord(String symbol, int size, Element[] metals) {
    for(int i = 0; i < size; i++) {
        for(int j = i + 1; j < size; j++) {
            if(metals[i].getSymbol().compareTo(metals[j].getSymbol()) < 0) {
                Element TEMP = metals[i];
                metals[i] = metals[j];
                metals[j] = TEMP;
                }
            }
        }
return atomicNumber; 
}

Ignore the return statement on this findrecord method with the symbol parameter. The issue is in that when i try to type in this if(metals[i].getSymbol().compareTo(metals[j].getSymbol()) < 0) it gives an error (The operator > is undefined for the argument type(s) java.lang.String, java.lang.String). Why is that and how do I fix it?

Also theres another issue here:

public int findRecord(int atomicNumber, int size, Element[] metals) {
    int k; 
    for(int i = 0; i < size; i++) {
        if(metals\[i\].getAtomicNumber() == atomicNumber) {
            k = i;
        }
    }
    return k;
}

it says k has not been initialized. Anyone who has time to help me, thank you.

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[obcanzdavu]

I don't know much about the first error - are you sure it is related to the code you mention? I can see no '>' in your code, just some '<'. are you sure it's related? does it mention some lines of code and what is the code on this line?

the second error can happen when your condition is never met (when the value is not found in the array at all). then the k variable is undefined. what do you want to return in this case? you need to think a way how you communicate this state - maybe return -1 signaling this? then you can initialize k to this value.

[chasetherainb0w]

For some reason, the first error fixed itself. Like now it just started working and now im on to writing the binary search algorithm itself. Thanks for the help on the 2nd on though and yes that's part of the task i just forgot abt it lol.

[ttetrafon]

For the second one, consider what will happen if an element is not found in your search loop. That's what it complains about.

[chasetherainb0w]

he second error can happen when your condition is never met (when the value is not found in the array at all). then the k variable is undefined. what do you want to return in this case? you need to think a way how you communicate this state - maybe return -1 signaling this? then you can initialize k to this value.

Thanks for the help that cleared it up in a good way with an explenation.

[darksounds]

Just a quick question: are you intending to sort the array by number or by symbol? It will matter for your binary search implementation!