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| − | =Review Questions= | + | {{Template:1010Topic |
| | + | |Chapter_TOC=[[User Defined Methods]] |
| | + | |Previous=[[Passing Arguments using Methods]] |
| | + | |Next=[[Arrays]] |
| | + | |Body= |
| | | | |
| − | 1. Explain the relationship between an argument and its corresponding parameter. Do not define '''argument''' or '''parameter'''.
| + | ==Introduction== |
| | + | To familiarize yourself with creating user-defined methods, this page contains review questions and exercises found in the Program A Day section. |
| | | | |
| − | '''Answer:''' During a method call, the calling method passes one argument to each parameter of the called method.
| + | =Try These Program A Day Questions= |
| | | | |
| | + | ==User Defined Methods== |
| | + | # [[Print a Calendar]] |
| | + | # [[Print Numbers]] |
| | + | # [[Add Area Code]] |
| | + | # [[Fix Code Sample]] |
| | + | # [[Concatenate Strings]] |
| | | | |
| − | 2. Which of the following methods completes execution first? What does this tell you about the order in which nested methods are executed?
| + | ==User Defined Methods Involving Arrays== |
| | + | # [[Passing Arrays]] |
| | + | # [[PrintArray Method]] |
| | + | # [[FillArray Method]] |
| | + | # [[ReverseArray Method]] |
| | + | # [[commissionCalculator]] |
| | + | # [[Cellphone Texting]] |
| | | | |
| − | <pre>
| + | ==Tougher Examples== |
| − | System.out.println( JOptionPane.showInputDialog("Please enter a message:") );
| + | # [[Rock Paper Scissors]] |
| − | </pre>
| + | # [[Student Record List With Parallel Arrays]] |
| − | | + | # [[Top Secret]] |
| − | Answer: '''JOptionPane.showInputDialog''' executes first, then passes its return value as an argument to '''System.out.println'''.
| + | # [[String Binary Search]] |
| − | When method calls are nested, the ''inner-most'' methods are executed first, because the outer methods need the inner methods' return values.
| + | }} |
| − | | + | |
| − | =Exercises= | + | |
| − | 1. Write a user-defined method which has an ''int'' parameter called '''numReps''' and returns a ''String''. The ''String'' will contain a sequence.
| + | |
| − | *If '''numReps''' is odd, the sequence is "+-".
| + | |
| − | *If '''numReps''' is even, the sequence is "/_".
| + | |
| − | The parameter '''numReps''' determines how many times the sequence is repeated in the ''String''. For example:
| + | |
| − | *When '''numReps''' is 2, the pattern is "/_/_".
| + | |
| − | *When '''numReps''' is 5, the pattern is "+-+-+-+-+-".
| + | |
| − | | + | |
| − | When you are finished, write a main method which tests your new user-defined method. Try the inputs 3, 4, and 0.
| + | |
| − | | + | |
| − | '''Solution:'''
| + | |
| − | | + | |
| − | <pre>
| + | |
| − | public class PatternSequence
| + | |
| − | {
| + | |
| − | /**
| + | |
| − | * This method creates a String consisting of a repeated series of characters.
| + | |
| − | *
| + | |
| − | * @param numReps - The number of times to repeat the sequence.
| + | |
| − | *
| + | |
| − | * @return String result - The built String.
| + | |
| − | */
| + | |
| − | public static String buildSequence(int numReps)
| + | |
| − | {
| + | |
| − | String pattern; // Either "+-" or "/_"
| + | |
| − | String result = ""; // The String to return
| + | |
| − | | + | |
| − | // If numReps is even, the pattern is "/_"
| + | |
| − | if(numReps % 2 == 0)
| + | |
| − | {
| + | |
| − | pattern = "/_";
| + | |
| − | }
| + | |
| − | | + | |
| − | // If numReps is odd, the pattern is "+-"
| + | |
| − | else
| + | |
| − | {
| + | |
| − | pattern = "+-";
| + | |
| − | }
| + | |
| − | | + | |
| − | // numReps determines how many times the pattern is repeated
| + | |
| − | for(int i=0; i<numReps; i++)
| + | |
| − | {
| + | |
| − | result += pattern;
| + | |
| − | }
| + | |
| − | | + | |
| − | return result;
| + | |
| − | }
| + | |
| − | | + | |
| − | // Main method
| + | |
| − | public static void main(String[] args)
| + | |
| − | {
| + | |
| − | // Let's test this out!
| + | |
| − | System.out.println(buildSequence(3));
| + | |
| − | System.out.println(buildSequence(4));
| + | |
| − | System.out.println(buildSequence(0));
| + | |
| − | | + | |
| − | }
| + | |
| − | }
| + | |
| − | | + | |
| − | </pre>
| + | |
| − | | + | |
| − | | + | |
| − | 2. Write a user-defined method which calculates the area of a triangle, called ''getTriangleArea''. The formula is:
| + | |
| − | <pre>
| + | |
| − | base x height
| + | |
| − | area = _____________
| + | |
| − | | + | |
| − | 2
| + | |
| − | </pre>
| + | |
| − | | + | |
| − | All values are of the ''double'' type.
| + | |
| − | | + | |
| − | Next, write a method called ''printArea'' which accepts a '''base''' parameter and a '''height''' parameter. The method prints the base, height, and area. Within this method you will call ''getTriangleArea''.
| + | |
| − | | + | |
| − | Finally, write a main method which tests ''printArea''. Try the following inputs: base = 2, height = 4; base = 5, height = 3; base = 0, height = 17.
| + | |
| − | | + | |
| − | '''Solution:'''
| + | |
| − | | + | |
| − | <pre>
| + | |
| − | public class TriangleArea
| + | |
| − | {
| + | |
| − | /**
| + | |
| − | * This method calculates the area of a triangle.
| + | |
| − | *
| + | |
| − | * @param base - The size of the triangle base.
| + | |
| − | * @param height - The height of the triangle.
| + | |
| − | *
| + | |
| − | * @return double result - The area of the triangle.
| + | |
| − | */
| + | |
| − | public static double getTriangleArea(double base, double height)
| + | |
| − | {
| + | |
| − | double result = (base * height) / 2;
| + | |
| − | | + | |
| − | return result;
| + | |
| − | }
| + | |
| − | | + | |
| − | | + | |
| − | /**
| + | |
| − | * This method prints the base, height, and area of a triangle.
| + | |
| − | *
| + | |
| − | * @param base - The size of the triangle base.
| + | |
| − | * @param height - The height of the triangle.
| + | |
| − | *
| + | |
| − | * @return void
| + | |
| − | */
| + | |
| − | public static void printArea(double base, double height)
| + | |
| − | {
| + | |
| − | System.out.println("Base: " + base);
| + | |
| − | System.out.println("Height: " + height);
| + | |
| − | System.out.println("Area: " + getTriangleArea(base, height));
| + | |
| − | System.out.println();
| + | |
| − | }
| + | |
| − | | + | |
| − | // Main method
| + | |
| − | public static void main(String[] args)
| + | |
| − | {
| + | |
| − | // Let's test this out!
| + | |
| − | printArea(2, 4);
| + | |
| − | printArea(5, 3);
| + | |
| − | printArea(0, 17);
| + | |
| − | }
| + | |
| − | } | + | |
| − | | + | |
| − | </pre>
| + | |
To familiarize yourself with creating user-defined methods, this page contains review questions and exercises found in the Program A Day section.
