1Z0-811 Practice Test — Free Oracle Java Foundations 1Z0-811 Questions with Explanations

A programmer is writing code that needs to store the result of a comparison that checks whether a number is greater than 10. Which primitive type should be used for the variable that holds this result?

A developer writes: int a = 9; int b = 2; double result = a / b; System.out.println(result); What is the output?

What is the output?

```java

public class Test {
    public static void main(String[] args) {

String s1 = "hello"; String s2 = "hello"; System.out.println(s1.equals(s2));

}
}

```

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

A package named com.example.util is declared in a file. Where should the file be placed in the directory structure?

What is the output of the following code? int[] a = {1,2,3}; int[] b = a; b[0] = 99; System.out.println(a[0]);

What is the result of the following code? int[] arr = new int[3]; arr[3] = 5; System.out.println(arr[3]);

Refer to the exhibit. A Java program throws a NullPointerException. Which is the most likely cause?

Given the stack trace above, which line in MyClass.java caused the exception?

Exception in thread "main" java.lang.NullPointerException at MyClass.methodC(MyClass.java:25) at MyClass.methodB(MyClass.java:15) at MyClass.methodA(MyClass.java:10) at MyClass.main(MyClass.java:30)

A developer runs the command shown in the exhibit. The developer wants to ensure the application uses the latest available language features. Which action should the developer take?

A developer is preparing to run a Java application on a colleague's computer. The colleague has installed the Java Runtime Environment (JRE) but not the Java Development Kit (JDK). The developer needs to explain what the colleague can and cannot do. Which statement is accurate?

During execution, the JVM uses Just-In-Time (JIT) compilation. What is its primary benefit?

Which of the following scenarios demonstrates the most appropriate use of a continue statement?

In a Java method, a developer needs to skip the current iteration and move to the next when a certain condition is met inside a for loop. Which statement should be used?

A junior developer created a class 'BankAccount' with public fields for balance and account number. After deployment, users are able to set negative balances, causing issues. Which OOP principle should have been applied to prevent this?

Which of the following best demonstrates polymorphism in Java?

A developer is reviewing code that declares several numeric variables. Which of the following declarations correctly assigns a floating-point literal to a variable of type float without causing a compile-time error?

A logistics application needs to store a shipment's unique tracking code, which is a fixed 12-character alphanumeric identifier. The code must not be modified after it is assigned. Which Java type is the most appropriate to declare for storing this tracking code?

A Java class named 'Helper' is defined in package 'utils'. Another class in a different package tries to access a public method of Helper but receives a compilation error. The Helper class is declared as 'class Helper' (without public modifier). What is the likely issue?

A company manages employee data stored in an array of Employee objects. The HR application frequently needs to find an employee by ID. The current implementation uses a linear search through the array each time. Performance reports indicate that this search is becoming a bottleneck as the company grows. The array is not sorted, and the company does not want to sort it because the order is meaningful for display. The array is large and frequently updated. The development team considers several options to improve the search performance without changing the array order. Which approach should they implement?