Write a complete Java program that produces a dialog window containing the message HelloWorld!. Your program does nothing else. Write a complete Java program that behaves as follows. The program...

Write a complete Java program that produces a dialog window containing

the message HelloWorld!. Your program does nothing else.

Write a complete Java program that behaves as follows. The program

displays an input dialog window asking the user to enter a whole number.

When the user enters a whole number and clicks the OK button, the

window goes away and an output dialog window appears. This window

simply tells the user what number was entered. When the user clicks the

OK button in the window, the program ends. (Hey, this is only Chapter 2.

The programs will get complicated soon enough.)