Chapter 7

Question 1

What is required for method overloading in Java?

Answer 1

Method overloading requires that methods differ either by the number of parameters or the types of parameters. The return type alone cannot be used to distinguish between overloaded methods.

Question 2

How can you fix a method overloading error where two methods have the same name and parameters in Java?

Answer 2

You can either change the parameter type (e.g., use double for one method) or add a different number of parameters. The return type alone cannot distinguish overloaded methods.

Question 3

How do you declare an array in Java?

Answer 3

Arrays are declared using a reference type and square brackets:
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int[] numbers;

Question 4

How do you create an array in Java?

Answer 4

After declaring an array reference, you can create an array like this:
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numbers = new int[6];
Or in one statement:
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int[] numbers = new int[6];

Question 5

Can arrays hold different types of data in Java? Give an example.

Answer 5

Yes, arrays can hold any type of data, including primitive types or objects. Example:
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float[] temperatures = new float[100];

Question 6

What is the size of an array in Java and how is it specified?

Answer 6

The size of an array is a non-negative number and can be a literal, constant, or variable:
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final int ARRAY_SIZE = 6;
int[] numbers = new int[ARRAY_SIZE];

Question 7

How do you access an element in an array in Java?

Answer 7

You access an array element using its reference name and index. Indexes start at zero:
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int value = numbers[0];

Question 8

What is the purpose of the length field in an array?

Answer 8

The length field stores the size of the array. It can be used in loops to avoid errors:
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int size = numbers.length;

Question 9

How do you initialize an array with specific values in Java?

Answer 9

You can initialize an array using an initialization list:
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int[] days = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

Question 10

How do you copy the elements of one array to another in Java?

Answer 10

You can copy an array by iterating through and assigning each element:
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for (int i = 0; i < firstArray.length; i++) {
secondArray[i] = firstArray[i];
}

Question 11

What is a two-dimensional array in Java?

Answer 11

A two-dimensional array is an array of arrays, where each element is another array. Example:
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double[][] scores = new double[3][4];

Question 12

How do you declare and initialize a ragged array in Java?

Answer 12

A ragged array has rows with varying numbers of columns. Declare and initialize like this:
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int[][] ragged = new int[4][];
ragged[0] = new int[3];
ragged[1] = new int[4];

Question 13

Can arrays hold objects in Java? Give an example.

Answer 13

Yes, arrays can hold objects. For example, an array of String objects:
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String[] names = { “Bill”, “Susan”, “Steven”, “Jean” };

Question 14

How do you use array elements in a loop?

Answer 14

You can loop through array elements with a for loop:
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for (int i = 0; i < temperatures.length; i++) {
System.out.println(“Temperature “ + i + “: “ + temperatures[i]);
}

Question 15

How do you return an array from a method in Java?

Answer 15

You can return an array by specifying the return type as an array of the appropriate type:
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public static double[] getArray() {
double[] array = { 1.2, 2.3, 4.5, 6.7, 8.9 };
return array;
}

Question 16

What is the purpose of a sequential search in an array?

Answer 16

A sequential search checks each array element sequentially to find a specific value. It stops once the value is found or the array is fully checked.

Question 17

What is the difference between an array’s length field and a String’s length() method?

Answer 17

The length field gives the size of the array, while String’s length() is a method that returns the number of characters in the string.

Question 18

How do you initialize a two-dimensional array in Java?

Answer 18

You initialize it using nested braces:
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int[][] numbers = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} };

Question 19

What does a selection sort do?

Answer 19

It finds the smallest value in the array and moves it to the first position, then repeats for the next smallest values until the array is sorted.

Question 20

In a binary search, what is the prerequisite for the array?

Answer 20

The array must be sorted in ascending order.

Question 21

Describe the process of a binary search.

Answer 21

Check the middle element.
If it matches the desired value, the search ends.
If it’s greater than the desired value, search the first half.
If it’s less, search the second half.
Repeat with adjusted start and end points until the value is found or the range is empty.

Question 22

What is the header of the main method that allows Java to receive command-line arguments?

Answer 22

public static void main(String[] args)

Question 23

How can arguments passed to the main method be accessed?

Answer 23

They can be accessed via the args array. For example, args[0], args[1], etc.

Question 24

What does the … symbol in a method parameter mean in Java?

Answer 24

It indicates a vararg (variable-length argument) parameter.

Question 25

Provide an example of a method that uses a vararg parameter.

Answer 25

public static int sum(int… numbers) {
int total = 0;
for (int val : numbers) {
total += val;
}
return total;
}

Question 26

What are the advantages of using an ArrayList over an array in Java?

Answer 26

Automatically resizes when items are added or removed.
Provides methods like add, remove, get, and size.

Question 27

How do you declare and initialize an ArrayList in Java?

Answer 27

ArrayList<String> nameList = new ArrayList<>();</String>

Question 28

How do you add an element to an ArrayList?

Answer 28

Use the add method:

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nameList.add(“James”);

Question 29

How do you get the size of an ArrayList?

Answer 29

nameList.size();

Question 30

How do you access an element in an ArrayList?

Answer 30

Use the get method:

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nameList.get(index);

Question 31

How do you remove an element from an ArrayList by index?

Answer 31

nameList.remove(index);

Question 32

How do you replace an element in an ArrayList?

Answer 32

Use the set method:

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nameList.set(index, “NewValue”);

Question 33

What is the default capacity of an ArrayList in Java?

Answer 33

10 items.

Question 34

How do you specify a custom capacity for an ArrayList?

Answer 34

ArrayList<String> list = new ArrayList<>(100);</String>

Question 35

What does the toString method of an ArrayList do?

Answer 35

Returns a string representation of all items in the list.

Question 36

What is the diamond operator (<>) in Java?

Answer 36

A shorthand introduced in Java 7 for simpler ArrayList declarations:
ArrayList<String> list = new ArrayList<>();</String>