1Z0-829 Controlling Program Flow Practice Test 3 — 15 Questions

Question 1

A developer is iterating over an array of sensor readings and needs to skip any reading whose value is negative while still processing the remaining readings. The loop is:

```java
int[] readings = {5, -1, 8, -3, 2};
int total = 0;
for (int r : readings) {
    if (r < 0) {
        continue;
    }
    total += r;
}
System.out.println(total);
```

What is printed?

Accepted Answer

15. The continue statement terminates the current iteration and proceeds with the next one, so guarded elements are excluded from the accumulation while all other elements are processed. Because only -1 and -3 satisfy the guard, they are skipped and the positives 5, 8, and 2 are summed to 15. The loop still visits every element, so no reading is silently dropped without evaluation.

Answer

9

Answer

11

Answer

The loop throws an exception when a negative value is encountered.

Question 2

A developer is writing a method that validates a numeric code and must use a switch expression that returns a String. The code must handle values 1 and 2 with distinct messages, treat any other positive value as unknown, and treat zero or negative values as invalid. Which two statements about switch expressions in Java 17 are correct? (Choose two.)

Accepted Answer

A switch expression may use the arrow (->) form, and each arm's body can be a single expression whose value is yielded implicitly.. Switch expressions require exhaustiveness and support the arrow form, where a single-expression arm yields its value implicitly. The validation logic can therefore map 1 and 2 to specific strings, use a default for other positive values, and still be forced by the compiler to handle every int input. Colon labels with fall-through remain a statement feature and are not allowed to fall through in an expression.

Answer

A switch expression can only be used as the initializer of a local variable and cannot appear as a method argument.

Answer

A switch expression may return different types from different arms, and the compiler infers a common supertype automatically.

Answer

A switch expression arm may use the traditional colon (:) syntax combined with implicit fall-through to the next arm.

Question 3

A developer is reviewing code that uses a for loop to iterate over an array. Which TWO statements about the for loop are correct? (Choose two.)

Accepted Answer

The condition expression in a for loop must be a boolean expression.. The for loop's update expression can contain multiple statements separated by commas, allowing multiple variables to be updated in one place. Also, the condition expression must be a boolean; any other type will cause a compilation error. These two statements accurately describe Java's for loop syntax and behavior.

Answer

The update expression in a for loop is executed before the condition is checked for the first time.

Answer

The initialization expression in a for loop is optional and can be omitted.

Answer

The initialization expression in a for loop can declare multiple variables of different types.

Question 4

A developer is writing a method to validate a configuration string. The method must iterate over each character in the string and, when it encounters a digit, skip that character and continue with the next one. Which loop construct and control statement should be used to achieve this?

Accepted Answer

A for loop with a continue statement when a digit is found.. The for loop with continue allows iterating with an index, skipping the current iteration when a digit is found, and continuing with the next character. The index is available for logging. Other options either terminate the loop prematurely or lack index access.

Answer

An enhanced for loop with a continue statement when a digit is found.

Answer

A do-while loop with a return statement when a digit is found.

Answer

A while loop with a break statement when a digit is found.

Question 5

A developer writes code to iterate over a list of strings and print each element. The code uses an enhanced for loop. Which statement is true about the enhanced for loop?

Accepted Answer

It can be used with arrays and any object that implements Iterable.. The enhanced for loop (for-each) in Java can iterate over arrays and any object that implements the Iterable interface, which includes all Collection classes (e.g., List, Set, Queue). This is because the for-each loop internally uses an iterator for Iterable objects or array indexing for arrays, making it a versatile construct for traversing elements without needing an explicit counter.

Answer

It can only be used with arrays.

Answer

It requires an explicit counter variable.

Answer

It allows removing elements from the collection during iteration without ConcurrentModificationException.

Question 6

Given the code snippet:
int x = 10;
if (x > 5) {
    System.out.print("A");
} else if (x > 7) {
    System.out.print("B");
} else {
    System.out.print("C");
}
What is the output?

Accepted Answer

A. The if-else chain evaluates conditions sequentially. Since x=10 satisfies x > 5, the first block executes and prints 'A'. The else if and else branches are skipped entirely because the first condition was true. Thus, only 'A' is output.

Answer

C

Answer

ABC

Answer

B

Question 7

A method contains a try-with-resources statement that uses two resources: a FileInputStream and a BufferedInputStream. The FileInputStream constructor throws a FileNotFoundException. Which statement about resource closing is true?

Accepted Answer

No resources are closed because the FileInputStream constructor failed before any resource was opened.. In a try-with-resources statement, resources are closed only if they have been successfully initialized. If the FileInputStream constructor throws a FileNotFoundException, the resource is never created, so the try-with-resources statement does not attempt to close it. The BufferedInputStream is never constructed because the exception occurs before its declaration is reached, so no resources are opened and none need to be closed. Therefore, option C is correct.

Answer

The BufferedInputStream is closed if it was successfully created, but the FileInputStream is not.

Answer

Both resources are closed even if the FileInputStream constructor throws an exception.

Answer

The programmer must explicitly close the resources in a finally block.

Question 8

Which TWO statements are true about the switch statement in Java?

Accepted Answer

It can be used with String objects.. Java's switch statement supports String objects since Java 7, allowing comparison based on the string's hashCode() and equals() methods. Option D is correct because switch can be used as an expression (e.g., with the arrow syntax) that yields a value, which can be assigned to a variable or returned.

Answer

Case values can be variables that are not final.

Answer

It requires a default case.

Answer

Each case must have a unique code block.

Question 9

Which THREE statements are true about loops in Java?

Accepted Answer

The break statement can be used to exit a loop prematurely.. The break statement in Java is used to immediately terminate the execution of a loop (for, while, or do-while) and transfer control to the statement following the loop. This allows premature exit based on a condition, which is a fundamental control flow mechanism in Java.

Answer

A while loop always executes at least once.

Answer

A do-while loop may execute zero times if the condition is false.

Question 10

Which loop construct guarantees that the body executes at least once?

Accepted Answer

do-while loop. The do-while loop is the only loop construct in Java that guarantees the body executes at least once because the condition is evaluated after the loop body. This post-test loop design ensures that regardless of the initial condition value, the body runs before any check occurs.

Answer

for loop

Answer

enhanced for loop

Answer

while loop

Question 11

Given the following Java code:

```java
for (int i = 0; i <= 2; i++) {
    for (int j = i; j <= i+2; j++) {
        if (j <= 3) {
            System.out.print(j + " ");
        }
    }
}
```

What is the output?

Accepted Answer

0 1 2 1 2 3 2 3. The program uses nested for loops. The outer loop iterates i from 0 to 2 (inclusive). For each i, the inner loop iterates j from i to i+2 (inclusive), but due to a condition that prevents printing values greater than 3, the inner loop effectively prints j only up to 3. Thus, for i=0 it prints 0,1,2; for i=1 it prints 1,2,3; for i=2 it prints 2,3. Combined on one line, the output is '0 1 2 1 2 3 2 3', which corresponds to option B.

Answer

0 1 2 1 2 3 2 3 4

Answer

0 1 2 1 2 3 2 3 4 5

Answer

0 1 2 1 2 3 2 3 3 4

Question 12

Which TWO statements about the switch statement in Java are true?

Accepted Answer

A break statement is optional.. Option A is correct because the break statement in a Java switch is optional; without it, control falls through to subsequent case labels, which is legal (though often unintended). Option D is correct because since Java 7 the switch expression may be of type String, in addition to the integral types char, byte, short, int, and their wrappers, plus enum. Option B is not correct because a switch can only be used as an expression in the newer arrow-style switch expressions (Java 14+), not in all cases such as the traditional colon-style switch statement. Option C is not correct because long is not an allowed type for a switch expression in Java; only int-compatible types, String, and enums are permitted. Option E is not correct because case labels must be compile-time constant expressions, not variables.

Answer

A switch statement can be used as an expression in all cases.

Answer

The switch expression can be of type long.

Answer

The case values can be variables.

Question 13

Given the following code fragment:
```java
int x = 0;
for (int i = 0; i < 4; i++) {
    x++;
}
System.out.println(x);
```
What is the result?

Accepted Answer

4. The loop runs four times (i = 0, 1, 2, 3), incrementing x each time. Therefore, x becomes 4, so the output is 4. Option B is correct.

Answer

9

Answer

3

Answer

5

Question 14

Order the steps to properly handle resources using try-with-resources in Java.

Accepted Answer

Step 1: Declare and initialize resources in the try-with-resources parentheses. Step 2: Use the resources in the try block. Step 3: Resources are automatically closed in reverse order of declaration.. try-with-resources ensures each resource is closed at the end of the statement. Resources are closed in the opposite order they were created.

Answer

Step 1: Use resources in try block. Step 2: Declare resources in try-with-resources. Step 3: Resources are closed in declaration order.

Answer

Step 1: Declare resources in try-with-resources. Step 2: Close resources manually in a finally block. Step 3: Use resources in try block.

Answer

Step 1: Use resources in try block. Step 2: Declare resources in try-with-resources. Step 3: Resources are closed automatically in declaration order.

Question 15

Order the steps to handle checked exceptions in a method that throws IOException.

Accepted Answer

1. Locate the code that throws IOException. 2. Enclose the code in a try block. 3. Add a catch block for IOException. 4. Provide exception handling code in the catch block.. Checked exceptions must be either caught or declared in the method signature. Unhandled checked exceptions cause compilation errors.

Answer

1. Locate the code that throws IOException. 2. Add a catch block for IOException. 3. Enclose the code in a try block. 4. Add a finally block.

Answer

1. Locate the code that throws IOException. 2. Add a finally block. 3. Add a try block. 4. Add a catch block.

Answer

1. Locate the code that throws IOException. 2. Continue writing code without any exception handling. 3. Assume the program will not throw IOException. 4. Compile and ignore errors.