INTRODUCTION TO OBJECTS AND INPUT/OUTPUT - Java Programming: From Problem Analysis to Program Design - page 170

18. Consider the statements:
double x = 75.3987;
double y = 982.89764;
What is the output of the following statements?

a. System.out.printf("%.2f %n", x);
b. System.out.printf("%.2f %n", y);
c. System.out.printf("%.3f %n", x);
d. System.out.printf("%.3f %n", y);
19. Consider the statements:
int x, y;
char ch;
and the input:
46 A 49

Write the Java statements that would store 46 into x , 'A' into ch ,and 49 into y .
20. The following program is supposed to read two numbers from a file named
Ex20Input.txt , and write the sum of the numbers to a file named
Ex20Output.dat .However,itfailstodoso.Rewritetheprogramsothatit
performs correctly. (You may assume that both numbers are on the same line.)
import java.util.*;

public class Ch3Ex20
{

public static void main(String[] args)
{

Scanner inFile ¼
new Scanner ( new FileReader("Ex20Input.txt"));

int num1, num2;

num1 = inFile.nextInt();
num2 = inFile.nextInt();

outFile.println("Sum = " + (num1 + num2));

outFile.close();

}

}
21. Which package must be imported to use the class PrintWriter ?
22.

Suppose that infile is a Scanner object and employee.dat is a file that
contains employees' information. Write the Java statement that opens this
file using the variable infile .