5.1 | What are the benefits of using a method? How do you declare a method? How do you invoke a method? |
5.2 | What is the return type of a main method? |
5.3 | Can you simplify the max method in Listing 5.1 using the conditional operator? |
5.4 | True of false? A call to a method with a void return type is always a statement itself, but a call to a method with a nonvoid return type is always a component of an expression. |
5.5 | What would be wrong with not writing a return statement in a nonvoid method? Can you have a return statement in a void method, such as the following? public static void main(String[] args) { int i; while ( true ) { // Prompt the user to enter an integer String intString = JOptionPane.showInputDialog( "Enter an integer:" ); // Convert a string into int int i = Integer.parseInt(intString); if (i == ) return ; System.out.println( "i = " + i); } } Does the return statement in the following method cause syntax errors? public static void xMethod( double x, double y) { System.out.println(x + y); return x + y; } |
5.6 | Define the terms parameter, argument, method signature. |
5.7 | Write method headers for the following methods :
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5.8 | Identify and correct the errors in the following program: 1 public class Test { 2 public static method1( int n, m) { 3 n += m; 4 xMethod( 3.4 ); 5 } 6 7 public static int xMethod( int n) { 8 if (n > ) return 1 ; 9 else if (n == ) return 0 ; 10 else if (n < ) return -1 ; 11 } 12 } |
5.9 | Reformat the following program according to the programming style and documentation guidelines proposed in §2.14, "Programming Style and Documentation." Use the next -line brace style. public class Test { public static double xMethod( double i, double j) { while (i<j) { j ” ”; } return j; } } |
5.10 | How is an argument passed to a method? Can the argument have the same name as its parameter? |
5.11 | What is pass- by-value ? Show the result of the following programs: |
5.12 | For (a) in the preceding question, show the contents of the stack just before the method max is invoked, just entering max , just before max is returned, and right after max is returned. |
5.13 | What is method overloading? Is it possible to define two methods that have the same name but different parameter types? Is it possible to define two methods in a class that have identical method names and parameter lists but with different return value types or different modifiers? |
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5.14 | What is wrong in the following program? public class Test { public static void method( int x) { } public static int method( int y) { return y; } } |
5.15 | Identify and correct the errors in the following program: 1 public class Test { 2 public static void main(String[] args) { 3 nPrintln( "Welcome to Java!", 5 ); 4 } 5 6 public static void nPrintln(String message, int n) { 7 int n = 1 ; 8 for ( int i = ; i < n; i++) 9 System.out.println(message); 10 } 11 } |
5.16 | True or false? The argument for trigonometric methods represents an angle in radians. |
5.17 | Write an expression that returns a random integer between 34 and 55 . Write an expression that returns a random integer between and 999 . Write an expression that returns a random number between 5.5 and 55.5 . Write an expression that returns a random lowercase letter. |
5.18 | Evaluate the following method calls: A. Math.sqrt(4) B. Math.sin(2 * Math.PI) C. Math.cos(2 * Math.PI) D. Math.pow(2, 2) E. Math.log(Math.E) F. Math.exp(1) G. Math.max(2, Math.min(3, 4)) H. Math.rint(-2.5) I. Math.ceil(-2.5) J. Math.floor(-2.5) K. Math.round(-2.5f) L. Math.round(-2.5) M. Math.rint(2.5) N. Math.ceil(2.5) O. Math.floor(2.5) P. Math.round(2.5f) Q. Math.round(2.5) R. Math.round(Math.abs(-2.5)) |
5.19 | What are the benefits of using packages? |
5.20 | If a class uses the package statement " package java.chapter5 ", where should the source code be stored, and where should the .class files be stored? How do you make the class available for use by other programs? |
5.21 | Why do you have to import JOptionPane but not the Math class? |