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The correct answer to the quiz is the program output shown below:
Original array contents
10 11 12 13 14 15 16 17Collection contents
B0 B1 L2 B3 B4 L5New array contents
B0 B1 L2 B3 B4 L5 null 17Modified array contents
XX B1 L2 B3 B4 L5 null 17Collection contents
XX B1 L2 B3 B4 L5 If that was your answer, you probably already understand most of the material covered in this module. In that case, you might consider skipping this moduleand moving on to some more productive activity. If that wasn't your answer, you should probably continue with your study of this module.
Except for the use of a different version of the toArray method, the overall structure of the program in Listing 1 is similar to the program in the previous module. Therefore, I will concentrate on those aspects of this programthat differentiate it from the program in the previous module.
Unlike the program in the previous module, the code in Listing 2 creates and populates an eight-element array of type JComponent . This array will be re-populated by the toArray method later in the program. The array is populated with a set of initial element values at this point to make itobvious when it is re-populated (overwritten elements) by the toArray method later.
| Listing 2 . A populated array. |
|---|
JComponent[] array = new JComponent[8];
for(int cnt=0;cnt<8;cnt++){
array[cnt]= new JButton();
array[cnt].setToolTipText("" + (cnt+10));
}//end for loopSystem.out.println();
showArray(array,"Original array contents"); |
The JButton class, the JLabel class, and the setToolTipText method were discussed in detail in the previous module, so I won't repeat thatdiscussion here.
After the array is populated by the code in Listing 2 , a reference to the array object is passed to the showArray method (also in Listing 2 ) to display the contents of the array.
With the exception of some minor changes implemented in this program to make the use of the showArray method more compact, this is the same showArray method used in the previous module. Therefore, I won't discuss that method further in this module. The output produced by the code in Listing 2 is as follows:
Original array contents
10 11 12 13 14 15 16 17 As you can see, each of the eight elements in the array was initialized with an easily-recognizable and unique value, ( which may be overwritten by the toArray method later).
The code in Listing 3 creates and populates a new LinkedList collection. The collection is populated by passing the LinkedList object's reference to a method named fillIt .
The code in Listing 2 also displays the contents of the LinkedList collection after it has been populated. The list is displayed by passing the LinkedList object's reference to a method named showCollection .
| Listing 3 . A new LinkedList collection. |
|---|
ref = new LinkedList();
Populator.fillIt(ref);showCollection(ref,"Collection contents"); |
Except for a couple of minor changes to the showCollection method, the code to create, populate, and display the collection is the same as the code inthe previous module.
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