Calling Methods Solutions

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Introduction These are the solutions for the review questions and exercises from Calling Methods
		Overview Make sure you fully understand all the solutions to these problems before continuing to the next chapter

Solutions

Review Questions

Question 1

Use the String class' .equals() method.

Question 2

Yes, using the String class' .equalsIgnoreCase() method.

Question 3

Use Math.pow(). The first argument is the number you are squaring, and the second parameter is 2.

Question 4

Use Math.sqrt().

Question 5

The Icon, message, input value and option buttons.

Question 6

Use JOptionPane.showInputDialog().

Question 7

The 4 default buttons are Yes, No, Ok, and Cancel.

Question 8

The purpose of ConfirmDialog box is to allow confirmation of user action.

Question 9

Use JOptionPane.showMessageDialog().

Question 10

Integer.parseInt(string_value) will return the integer value of string_value. The characters in string_value must all be decimal digits, except the first character which can be a minus sign.

Programming Excercises

Exercise 1

import javax.swing.JOptionPane;

public class Test
{
	public static void main(String[] args)
	{
		String input; // User's input
		int first; // First input number
		int second; // Second input number
		int min; // Min of first and second

		// Get user input and put it into an integer
		input = JOptionPane.showInputDialog("Please input the first number");
		first = Integer.parseInt(input);

		// Get user input and put it into another integer
		input = JOptionPane.showInputDialog("Please input the second number");
		second = Integer.parseInt(input);

		// Get the smaller of the two numbers
		min = Math.min(first, second);

		// Print out the result
		System.out.println(min);

		// End the program
		System.exit(0);
	}
}

Exercise 2

import javax.swing.JOptionPane;

public class Test
{
	public static void main(String[] args)
	{
		String input; // User input
		int exponent; // Exponent we will be using
		double result; // 2 ^ exponent

		// Get exponent from user, and put it into an integer
		input = JOptionPane.showInputDialog("Please input the exponent");
		exponent = Integer.parseInt(input);

		// Raise 2 to the power of the input exponent
		result = Math.pow(2, exponent);

		// Print out the result
		System.out.println(result);

		// End the program
		System.exit(0);
	}
}

Exercise 3

import javax.swing.JOptionPane;

public class Test
{
	public static void main(String[] args)
	{
		String input; // User input
		int low; // Lower bound for random number
		int high; // Upper bound for random number
		long result; // The random number

		// Get lower bound from user and put it into an int
		input = JOptionPane.showInputDialog("Please input lower bound");
		low = Integer.parseInt(input);

		// Get upper bound from user and put it into an int
		input = JOptionPane.showInputDialog("Please input upper bound");
		high = Integer.parseInt(input);

		// Compute a random number between low and high inclusive
		result = (int)(Math.random() * (high - low + 1)) + low;

		// Print out the result
		System.out.println(result);

		// End the program
		System.exit(0);
	}
}