1Z0-811 Practice Test 4 — 10 Questions

Question 1

int count = 0;
for (int i = 0; i < 5; i++) {
    if (i == 2) {
        continue;
    }
    count++;
}
System.out.println(count);

What is the output of the program?

Accepted Answer

4. The loop runs i from 0 to 4. When i equals 2, the continue statement skips the rest of the loop body, so count++ is not executed for that iteration. For the other four iterations (i = 0, 1, 3, 4), count is incremented, giving a final value of 4.

Answer

The loop does not compile.

Answer

5

Answer

2

Question 2

Given: boolean a = false; boolean b = true; boolean c = true; System.out.println(a || b && c); What is the output?

Accepted Answer

true. In Java, the logical AND operator (&&) has higher precedence than the logical OR operator (||). Therefore, the expression `a || b && c` is evaluated as `a || (b && c)`. Given `a = false`, `b = true`, and `c = true`, `b && c` evaluates to `true`, and then `false || true` evaluates to `true`. Thus, the output is `true`, making option D correct.

Answer

false

Answer

Compilation fails

Answer

None of the above

Question 3

A developer compiles a Java application using the command `javac -d bin src/com/example/App.java`. Which of the following is true?

Accepted Answer

The compiled .class files are placed in the `bin` directory maintaining the package structure.. The `-d` option in the `javac` command specifies the destination directory for compiled `.class` files. When `-d bin` is used, the compiler places the `.class` files into the `bin` directory, preserving the package directory structure (e.g., `bin/com/example/App.class`). This is the standard behavior for organizing compiled output separately from source code.

Answer

The compiler searches for source files in the `bin` directory.

Answer

The compiler creates a JAR file named `App.jar` in the `bin` directory.

Answer

The compiler compiles the code into a named module.

Question 4

Which of the following correctly uses the shorthand array initializer to declare and initialize an array of strings with the elements "A", "B", and "C"?

Accepted Answer

String[] arr = {"A", "B", "C"};. Option D correctly uses the shorthand array initializer with curly braces directly in the declaration. Option A uses the full syntax with the 'new' keyword, which is also valid but not the shorthand. Option B is wrong because it uses parentheses. Option C is wrong because it uses square brackets.

Answer

String[] arr = new String[] {"A", "B", "C"};

Answer

String[] arr = ("A", "B", "C");

Answer

String[] arr = ["A", "B", "C"];

Question 5

Given the code: String s1 = "Java"; String s2 = new String("Java"); if (s1 == s2) { System.out.print("Equal"); } else { System.out.print("Not Equal"); } What is the output?

Accepted Answer

Not Equal. The == operator compares object references, not the actual string content. s1 is a string literal stored in the string pool, while s2 is a new String object created on the heap, so they refer to different memory locations, making the comparison false and printing 'Not Equal'.

Answer

Runtime error

Answer

Compilation error

Answer

Equal

Question 6

A developer is working on a Java application that processes sensor data. The code uses a class 'SensorDataProcessor' which directly instantiates specific sensor classes like 'TemperatureSensor' and 'PressureSensor' inside its methods. The team wants to make the system extensible to support new sensor types without modifying the processor class. Which design change best achieves this?

Accepted Answer

Define a Sensor interface and use dependency injection to pass sensor objects to the processor. The Open/Closed Principle says classes should be open for extension but closed for modification. By defining a Sensor interface and injecting Sensor implementations into SensorDataProcessor, the processor depends on an abstraction rather than concrete classes, so new sensor types can be added without touching the processor code. Dependency injection also improves testability because mock sensors can be substituted in unit tests. This is the canonical Strategy/DI pattern for decoupling.

Answer

Make SensorDataProcessor abstract and subclass it for each sensor

Answer

Use a static factory method in SensorDataProcessor to create sensors

Answer

Create a separate configuration file listing sensors and use reflection to instantiate them

Question 7

A developer writes a utility that must return two values, a minimum and a maximum, from an array of measurements. The method below is proposed:

public static int[] minMax(int[] values) {
    // implementation omitted
    return new int[]{min, max};
}

Which statement about this method signature and return statement is correct?

Accepted Answer

The method compiles, and the returned array is a distinct object whose length is 2.. Array types are legitimate return types because arrays are objects, and an array initializer on a return statement allocates a brand-new two-element array on each invocation. The caller therefore receives an independent object whose length is fixed at two by the initializer.

Answer

The method compiles only if the array initializer is replaced with a call to Arrays.copyOf on the input parameter.

Answer

The method cannot compile because Java methods may return only primitive values or single objects, never arrays.

Answer

The method compiles, but the returned array automatically shares storage with the input parameter values.

Question 8

Which THREE of the following expressions compile without error? (Choose 3)

Accepted Answer

byte b = 1 + 2;. Option A is correct because the expression 1 + 2 is a compile-time constant int whose value (3) fits within the byte range, so the implicit narrowing assignment to byte is permitted. Option C is correct because an int literal 10 is widened automatically to double in the assignment double d = 10;. Option D is correct because (false || true) is a valid boolean expression using the logical OR operator, and its result is assignable to a boolean variable. Option B is not correct because 5L is a long and 10 is an int; the sum is long, which cannot be assigned to an int without an explicit cast. Option E is not correct because 5.5 is a double literal, and assigning a double to a float requires an explicit cast (or an f suffix such as 5.5f).

Answer

int i = 5L + 10;

Answer

float f = 5.5;

Question 9

Which operator is used to compare two strings for value equality in Java?

Accepted Answer

equals(). The equals() method in Java's String class compares the actual character sequences of two strings for value equality. Unlike the == operator, which checks reference equality (whether two references point to the same object in memory), equals() performs a lexicographic comparison of the string contents, returning true if and only if both strings have the same length and the same characters in the same order.

Answer

compareTo()

Answer

=

Answer

==