1Z0-808: Java SE 8 Programmer IDemo

Each variable has the declared type Employee, so compile-time member access permits its public salary field only. Although director refers to a Director object at runtime, fields such as budget and stockOptions are not accessible through an Employee-typed reference without a cast.

A break statement at the end of a case block is optional. If it is omitted and execution reaches the end of that block, control normally continues into the following case block (fall-through).

Java inserts an implicit super() call as the first statement of each constructor when no explicit constructor invocation is written. Creating C therefore runs A's constructor, followed by B's constructor, and finally C's constructor, producing A B C.

Java passes an int argument by value, so decrementing x inside isAvailable changes only that method's parameter, not the x declared in main. Pre-decrementing x in the print statement changes the main variable from 6 through 1, producing 54321; the next condition call receives 1, evaluates its local copy to 0, and terminates the loop.

Java passes primitive values by value. The doCalc method doubles only its local copy of var1 and returns 400; the var1 declared in main remains 200.

A static field is shared by every instance, while each instance has its own ns field. The second constructor call does not satisfy s < ns, so that object's ns remains its default value of 0. The third constructor call updates the shared s to 125; therefore all three print calls show s = 125, while the instance values are 100, 0, and 125, respectively.

The conditions must preserve discount = 0.5 for every qty value of 90 or more, while assigning discount = 0.2 only for values greater than 80 and less than 90. Separate non-overlapping if statements or a conditional expression that tests qty >= 90 before qty > 80 satisfy those ranges.

The interface supplies an abstract contract, and Game provides its concrete operations. A Playable reference holding a Game object demonstrates polymorphism because the interface type can refer to an implementing object and invoke its implemented behavior. The private players field, accessed through methods, demonstrates encapsulation.

The Java runtime environment invokes an application's designated main method to start execution. A conventional Java entry-point method has a void return type and is not required to be final or enclosed in a public class.

The one-argument constructor must initialize bounds while retaining Animal’s default type and maxSpeed, so it can call super() and assign this.bounds. The three-argument constructor must call super(type, maxSpeed) to initialize the inherited fields and then assign this.bounds. An explicit super(...) or this(...) constructor invocation must occur before ordinary constructor-body statements.

Arguments following the class name are passed to main. Quotation marks group whitespace-containing text into one argument, so args[0] is 1 2 3; concatenating it with String main prints String main 1 2 3.

Negating the current balance with setAmount(-getAmount()) makes the balance zero because changeAmount(0) adds nothing. The public amount field can be assigned directly from another class, and the public setAmount method can set the balance to zero. These three alternatives guarantee that the printed balance is 0.

A standard for loop can control the array index directly, allowing reverse traversal, normal forward traversal, and alternating-element traversal by changing the index start, condition, and increment. An enhanced for loop traverses an array sequentially in its entry order, so it can implement the forward-order requirement.

Polymorphism is demonstrated because a Playable reference holds a Game object. Abstraction is provided by the Playable interface, which declares behavior independently of its implementation. Encapsulation is demonstrated by the private players field and its public accessor and mutator methods.

Java bytecode is platform-independent intermediate code that can be transmitted across a network. It runs on systems that provide a compatible Java Runtime Environment, which includes the Java Virtual Machine needed to execute the bytecode.

Instance fields of primitive type int default to 0. Passing a Book reference allows the method to modify the referenced object's pages field, so it becomes 100. The int argument is passed by value, so assigning 200 to the parameter does not change count; it remains 0.

A switch case continues into the following case unless it encounters break. Processing "mon" increments the value and falls through to the "wed" case, while "sun" and "sat" each decrement it. The final value printed is 3.

Field access is checked against the variable’s declared reference type. An Employee reference has no budget field, so employee.budget is invalid. A Manager reference has no field named stockOption; moreover, the declared Director field is named stockOptions (plural) and is not a member of Manager. Public fields inherited from a superclass remain accessible through subclass references.

Java String values are immutable. Each assigned concat call extends ta, but the unassigned replace("B", "C") result is discarded, so B remains unchanged. The printed value is A B C D.

Encapsulation lets a class control access to its data and behavior by making only selected fields and methods accessible to other objects.

A Predicate<Integer> is evaluated with test(Integer). The predicate returns true for 100 because 100 is even, so printing that result outputs true.

A Java break statement must occur within a loop or switch statement. Here, the loop has already ended before break is reached, so the code does not compile.

String.concat returns a new string and does not alter the existing list element. The result produced during forEach is discarded, whereas List.replaceAll replaces every element with the result of its operator. The list therefore contains JavaGroup and ExpertGroup.

For an ArrayList<Integer>, remove(1) invokes the overload that removes the element at index 1, so it removes 2. Calling remove(null) invokes the overload that removes the specified object, removing the null element. The list therefore contains [1, 3, 4].