Java Programming :: Objects and Collections
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which statement is true?class Test1 { public int value; public int hashCode() { return 42; } } class Test2 { public int value; public int hashcode() { return (int)(value^5); } } -
Which statement is true for the class java.util.HashSet?
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Which of the following statements about the hashcode() method are incorrect?
- The value returned by hashcode() is used in some collection classes to help locate objects.
- The hashcode() method is required to return a positive int value.
- The hashcode() method in the String class is the one inherited from Object.
- Two new empty String objects will produce identical hashcodes.
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What two statements are true about properly overridden hashCode() and equals() methods?
- hashCode() doesn't have to be overridden if equals() is.
- equals() doesn't have to be overridden if hashCode() is.
- hashCode() can always return the same value, regardless of the object that invoked it.
- equals() can be true even if it's comparing different objects.
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Which two statements are true about comparing two instances of the same class, given that the equals() and hashCode() methods have been properly overridden?
- If the equals() method returns true, the hashCode() comparison == must return true.
- If the equals() method returns false, the hashCode() comparison != must return true.
- If the hashCode() comparison == returns true, the equals() method must return true.
- If the hashCode() comparison == returns true, the equals() method might return true.
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x = 0; if (x1.hashCode() != x2.hashCode() ) x = x + 1; if (x3.equals(x4) ) x = x + 10; if (!x5.equals(x6) ) x = x + 100; if (x7.hashCode() == x8.hashCode() ) = x + 1000; System.out.println("x = " + x);and assuming that the equals() and hashCode() methods are properly implemented, if the output is "x = 1111", which of the following statements will always be true?
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Which of the following are true statements?
- The Iterator interface declares only three methods: hasNext, next and remove.
- The ListIterator interface extends both the List and Iterator interfaces.
- The ListIterator interface provides forward and backward iteration capabilities.
- The ListIterator interface provides the ability to modify the List during iteration.
- The ListIterator interface provides the ability to determine its position in the List.
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Which statement is true for the class java.util.ArrayList?
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