Simple Java Quiz

Private attributes of a class can only be accessed by methods defined within the same class. This is encapsulation - private members are invisible outside the class boundary. Static methods are subject to the same rules as instance methods (no special access). Instances of the same class can't directly access private members of other instances. Classes in the same package have no special access to private members - they would need protected or package-private access modifiers.

The question asks which statement is FALSE. Objects DO permit encapsulation - it's a core OOP principle of bundling data and methods together. Option C correctly identifies the false statement.

An aggregate object is an object that contains other objects as its parts or attributes, representing a 'has-a' relationship. This is a core concept in object-oriented design and composition.

void indicates that a method returns no value. Option A is correct - void means the method returns nothing, not 'no data type' which is awkward phrasing but captures the intent.

Method overloading allows multiple methods with the same name but different parameter lists (number or type). This differs from overriding which is about subclass behavior.

To determine the value of fname after the given code fragment, we need to understand the indexOf() method in Java and how it is used.

The indexOf() method in Java returns the index of the first occurrence of a specified substring within a given string. It returns -1 if the substring is not found.

Now let's go through the code fragment and evaluate each line:

String str;
int fname;
str = ";Foolish boy.";
fname = str.indexOf("fool");

• String str; declares a variable str of type String.
• int fname; declares a variable fname of type int.
• str = ";Foolish boy."; assigns the string ";Foolish boy." to the variable str.
• fname = str.indexOf("fool"); assigns the return value of indexOf("fool") to the variable fname.

Now, let's evaluate each option and explain why it is right or wrong:

A. 0: This option is incorrect. The indexOf("fool") method call will return -1 because the substring "fool" is not found in the string str = ";Foolish boy.". Therefore, fname will be assigned the value -1, not 0.

B. 2: This option is incorrect. The indexOf("fool") method call will return -1 because the substring "fool" is not found in the string str = ";Foolish boy.". Therefore, fname will be assigned the value -1, not 2.

C. -1: This option is correct. The indexOf("fool") method call will return -1 because the substring "fool" is not found in the string str = ";Foolish boy.". Therefore, fname will be assigned the value -1.

D. 4: This option is incorrect. The indexOf("fool") method call will return -1 because the substring "fool" is not found in the string str = ";Foolish boy.". Therefore, fname will be assigned the value -1, not 4.

Therefore, the correct answer is:

C. -1

In Java, the trim() method returns a canonical string from the string pool if the resulting string is a literal. However, because trim() creates a new string object, == usually compares references. In many JVM implementations, this specific literal comparison might return true, but equals() is the proper way to compare content.

public is an access modifier, not a return type. Valid return types include primitive types like boolean, void, or object types like Button. Access modifiers control visibility, not what a method returns.

In Java, the Exception class extends Throwable. While it is also serializable, the most fundamental architectural definition in the context of the class hierarchy is its inheritance from Throwable.

charAt() is zero-indexed. 'Java' has indices 0-3 (J=0, a=1, v=2, a=3). Index 4 is out of bounds, so StringIndexOutOfBoundsException is thrown. Option C is correct.