(Create a histogram for occurrences of letters) The program in Listing 17.8, MultipleWin...

(Create a histogram for occurrences of letters) The program in Listing 17.8, MultipleWindowsDemo.java, displays a histogram to show the occurrences of each letter in a text area. Reuse the Histogram class created in Listing 17.9 to write a program that will display a histogram on a panel. The histogram should show the occurrences of each letter in a text file, as shown in Figure 17.20b. Assume that the letters are not case sensitive.

¦ Place the panel that will display the histogram in the center of the frame.

¦ Place a label and a text field in a panel, and put the panel in the south side of the frame. The text file will be entered from this text field.

¦ Pressing the Enter key on the text field causes the program to count the occurrences of each letter and display the count in a histogram.