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ch05a.html
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<!doctype html>
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<title>Java 8 Programmer II Study Guide: Exam 1Z0-809</title>
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<h1><i class="chapter">Chapter FIVE</i><br />
Enumerations</h1>
<p><br /></p>
<h3 style="text-align: center;"><i>Exam Objectives</i></h3>
<p style="text-align: center;"><i>Use enumerated types including methods, and constructors in an enum type.</i></p>
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<h2>Answers</h2>
<p><b>1. The correct answer is C.</b><br /> An <code>enum</code> is implicitly <code>static</code>. This makes the <code>printValue()</code> method execute in a <code>static</code> context. So, the reference in the method <code>printValue()</code> to the variable <code>value</code> is invalid, because <code>value</code> is non-static.</p>
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<p><b>2. The correct answer is A.</b><br /> There's nothing wrong with the code. Since <code>values()</code> returns an array of enums in the same order in which they were declared, <code>Blue</code> is returned, and <code>1</code> is printed.</p>
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<p><b>3. The correct answer is A.</b><br /> Option A is true. Enums are thread-safe.<br /> Option B is false. Enums can't extend from a class, but they can implement an interface.<br /> Option C is false. Enums can define <code>private</code> constructors.<br /> Option D is false. Enums can have setter methods.</p>
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<p><b>4. The correct answer is C.</b><br /> Enums are created just in time, the first time they are referenced. When variable <code>l1</code> is created, the enum <code>Level</code> is also created, calling the constructor of <code>HIGH</code> and <code>LOW</code> and printing <code>100</code> and <code>10</code>.</p>
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<p><b>5. The correct answer is B.</b><br /> Enums constants from different enumerations are not equal, even if they share the same name.</p>
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<p><b>6. The correct answers are A and B.</b><br /> Option A is true. You can compare two enumerations using the <code>==</code> operator.<br /> Option B is true. Enums implicitly inherit from <code>java.lang.Enum</code>.<br /> Option C is false. You can use the new operator inside an <code>enum</code>, but you cannot use the <code>new</code> operator to create a reference to an <code>enum</code>.<br /> Option D is false. You can have abstract methods inside an <code>enum</code>, but all <code>enum</code> constants must provide an implementation.</p>
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