Prentice.Hall.Introduction.to.Java.Programming,.Brief.Version.9th.(2014).[sharethefiles.com]

Write a test program that prompts the user to enter a decimal number and displays
its binary equivalent.
*20.22 (Decimal to hex) Write a recursive method that converts a decimal number into
a hex number as a string. The method header is:
public static String decimalToHex(int value)
Write a test program that prompts the user to enter a decimal number and displays
its hex equivalent.
*20.23 (Binary to decimal) Write a recursive method that parses a binary number as a
string into a decimal integer. The method header is:
public static int binaryToDecimal(String binaryString)
Write a test program that prompts the user to enter a binary string and displays
its decimal equivalent.
*20.24 (Hex to decimal) Write a recursive method that parses a hex number as a string
into a decimal integer. The method header is:
public static int hexToDecimal(String hexString)
Write a test program that prompts the user to enter a hex string and displays its
decimal equivalent.
**20.25 (String permutation) Write a recursive method to print all the permutations of a
string. For example, for the string abc, the printout is
abc
acb
bac
bca
cab
cba
(Hint: Define the following two methods. The second is a helper method.)
public static void displayPermutation(String s)
public static void displayPermutation(String s1, String s2)
The first method simply invokes displayPermutation(" ", s). The
second method uses a loop to move a character from s2 to s1 and recursively
invokes it with a new s1 and s2. The base case is that s2 is empty and prints s1
to the console.
Write a test program that prompts the user to enter a string and displays all its
permutations.
**20.26 (Create a maze) Write an applet that will find a path in a maze, as shown in
Figure 20.13a. The maze is represented by an 8 * 8 board. The path must meet
the following conditions:
■ The path is between the upper-left corner cell and the lower-right corner
cell in the maze.
■ The applet enables the user to place or remove a mark on a cell. A path consists
of adjacent unmarked cells. Two cells are said to be adjacent if they are
horizontal or vertical neighbors, but not if they are diagonal neighbors.
■ The path does not contain cells that form a square. The path in Figure
20.13b, for example, does not meet this condition. (The condition makes a
path easy to identify on the board.)
Programming Exercises 763