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POIterating through hashmap and creating unique objects - trying to prevent duplicates
 

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    <p>I explain what I am trying to do in comments above the parts in the method:</p> <pre><code>public int addPatron(String name) throws PatronException { int i = 0; //1. Iterate through a hashmap, and confirm the new name I am trying to add to the record doesn't already exist in the hashmap for (Map.Entry&lt;Integer, Patron&gt; entry : patrons.entrySet()) { Patron nameTest = entry.getValue(); //2. If the name I am trying to add already exists, we want to throw an exception saying as much. if (nameTest.getName() == name) { throw new PatronException ("This patron already exists"); //3. If the name is unique, we want to get the largest key value (customer number) already in the hash, an increment by one. } else if (nameTest.getName() != name) { Map.Entry&lt;Integer,Patron&gt; maxEntry = null; for(Map.Entry&lt;Integer, Patron&gt; entryCheck : patrons.entrySet()) { if (maxEntry == null || entryCheck.getKey() &gt; maxEntry.getKey()) { maxEntry = entryCheck; i = maxEntry.getKey(); i++; } } } else { throw new PatronException("Something's not working!"); } //4. If everything is ok up to this point, we want to us the name and the new customer id number, and use those to create a new Patron object, which then gets added to a hashmap for this class which contains all the patrons. Patron newPatron = new Patron(name, i); patrons.put(i, newPatron); } return i; } </code></pre> <p>When I try and run a simple unit test that will fail if I successfully add the same name for addPatron twice in a row, the test fails.</p> <pre><code>try { testLibrary.addPatron("Dude"); testLibrary.addPatron("Dude"); fail("This shouldn't have worked"); </code></pre> <p>The test fails, telling me the addPatron method is able to use the same name twice. </p> <p>@Jon Skeet:</p> <p>My Patron class looks like this:</p> <pre><code>public class Patron { //attributes private String name = null; private int cardNumber = 0; //operations public Patron (String name, int cardNumber){ this.name = name; this.cardNumber = cardNumber; } public String getName(){ return name; } public int getCardNumber(){ return cardNumber; } </code></pre> <p>}</p>
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    1. COnameTest.getName() == name should be nameTest.getName().equals(name)
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      1. USDiego Basch
    2. COIt seems you have a Map<Integer, String>, but you should have a Map<String, Integer>.
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      1. USJB Nizet
    3. CO@DiegoBasch: It should, but that wouldn't explain the exact test given failing, given the use of string literals (which would be interned).
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