java - 遍历 hashmap - 抛出异常

Question

这与我之前提出的一个问题有关: Iterating through hashmap and creating unique objects - trying to prevent duplicates

虽然我认为我可以为我的删除方法应用与我的添加方法类似的逻辑，但我必须检查不存在的记录的异常被抛出，即使我非常清楚该记录存在并且应该被删除。我的删除方法如下:

    public boolean removePatron(int libraryCardNumber) throws PatronException {
    boolean patronRemoved = false;
    int keyToRemove = 0;
    for (Map.Entry<Integer, Patron> entry : patrons.entrySet()) {
        if (entry.getValue().getCardNumber() != libraryCardNumber) {
            throw new PatronException("This record does not exist");

        }
        keyToRemove = entry.getKey();
    }
    patrons.remove(keyToRemove);
    patronRemoved = true;
    return patronRemoved;
}

作为引用，Patron 对象如下所示:

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;
}

 }

我的测试只是先添加三个顾客，然后尝试通过我知道存在的卡号将其删除。我在 add 方法中添加了赞助人号码的 println ，这样我就可以在添加它们时在 Eclipse 中搞乱它，从而轻松地看到它们。

    @Test
public void testRemovePatron() {
    boolean exceptionThrown = false;
    try {
        testLibrary.addPatron("TestName");
        testLibrary.addPatron("TestName2");
        testLibrary.addPatron("TestName3");
        testLibrary.removePatron(1);
    } catch (PatronException e) {
        System.out.println(e.getMessage());
        exceptionThrown = true;
        fail("what the hell is going on");
    }
    assertFalse(exceptionThrown);
}

我每次都会从删除方法中抛出异常。

编辑:我对提供的答案做了一个小小的更改，以考虑到如果没有找到匹配项则需要抛出异常:

    public boolean removePatron(int libraryCardNumber) throws PatronException {
    boolean patronRemoved = false;
    int keyToRemove = 0;
    for (Map.Entry<Integer, Patron> entry : patrons.entrySet()) 
    {
        if (entry.getValue().getCardNumber() == libraryCardNumber) 
        {
            keyToRemove = entry.getKey();
            patronRemoved = true;
        }
    }
    if (patronRemoved)
    {
        patrons.remove(keyToRemove);
    } else {
        throw new PatronException("This record did not exist");
    }
    return patronRemoved;
}

Answer 1

对于任何不是您要查找的用户的用户，都会引发异常。更改此:

public boolean removePatron(int libraryCardNumber) throws PatronException{
    boolean patronRemoved = false;
    int keyToRemove = 0;
    for (Map.Entry<Integer, Patron> entry : patrons.entrySet()) {
        if (entry.getValue().getCardNumber() != libraryCardNumber) {
            throw new PatronException("This record does not exist");

        }
        keyToRemove = entry.getKey();
    }
    patrons.remove(keyToRemove);
    patronRemoved = true;
    return patronRemoved;
}

对此:

public boolean removePatron(int libraryCardNumber) {
    boolean patronRemoved = false;
    int keyToRemove = 0;
    for (Map.Entry<Integer, Patron> entry : patrons.entrySet()) 
    {
        if (entry.getValue().getCardNumber() == libraryCardNumber) 
        {
            keyToRemove = entry.getKey();
            found = true;
        }
    }
    if (found)
    {
        patrons.remove(keyToRemove);
    }
    return patronRemoved;
}

或者更简洁，如 AmitD 所示