Introduction to Java Programming and Data Structures, 11E, Y. Daniel Liang

Chapter 2 Check Point Questions

Section 2.2

▼2.2.1

Identify and fix the errors in the following code:

 1  public class Test {
 2    public void main(string[] args) {
 3      double i = 50.0;
 4      double k = i + 50.0;
 5      double j = k + 1;
 6
 7      System.out.println("j is " + j + " and
 8        k is " + k);
 9    }
10  }

Section 2.3

▼2.3.1

How do you write a statement to let the user enter a double value from the keyboard? What happens if you entered 5a when executing the following code?

double radius = input.nextDouble();

▼2.3.2

Are there any performance differences between the following two import statements?

import java.util.Scanner; 
import java.util.*;

Section 2.4

▼2.4.1

Which of the following identifiers are valid? Which are Java keywords?

miles, Test, a++, --a, 4#R, $4, #44, apps
class, public, int, x, y, radius

Section 2.5

▼2.5.1

Identify and fix the errors in the following code:

1  public class Test {
2    public static void main(String[] args) {
3      int i = k + 2;
4      System.out.println(i);
5    }
6  }

Section 2.6

▼2.6.1

Identify and fix the errors in the following code:

1  public class Test {
2    public static void main(String[] args) {
3      int i = j = k = 2;
4      System.out.println(i + " " + j + " " + k);
5    }
6  }

Section 2.7

▼2.7.1

What are the benefits of using constants? Declare an int constant SIZE with value 20.

▼2.7.2

Translate the following algorithm into Java code:
Step 1: Declare a double variable named miles with initial value 100.
Step 2: Declare a double constant named KILOMETERS_PER_MILE with value 1.609.
Step 3: Declare a double variable named kilometers, multiply miles and KILOMETERS_PER_MILE, and assign the result to kilometers.
Step 4: Display kilometers to the console.
What is kilometers after Step 4?

Section 2.8

▼2.8.1

What are the naming conventions for class names, method names, constants, and variables? Which of the following items can be a constant, a method, a variable, or a class according to the Java naming conventions?

MAX_VALUE, Test, read, readDouble

Section 2.9

▼2.9.1

Find the largest and smallest byte, short, int, long, float, and double. Which of these data types requires the least amount of memory?

▼2.9.2

Show the result of the following remainders.

56 % 6
78 % -4
-34 % 5
-34 % -5
5 % 1
1 % 5

▼2.9.3

If today is Tuesday, what will be the day in 100 days?

▼2.9.4

What is the result of 25 / 4? How would you rewrite the expression if you wished the result to be a floating-point number?

▼2.9.5

Show the result of the following code:

System.out.println(2 * (5 / 2 + 5 / 2));
System.out.println(2 * 5 / 2 + 2 * 5 / 2);
System.out.println(2 * (5 / 2));
System.out.println(2 * 5 / 2);

▼2.9.6

Are the following statements correct? If so, show the output.

System.out.println("25 / 4 is " + 25 / 4);
System.out.println("25 / 4.0 is " + 25 / 4.0);
System.out.println("3 * 2 / 4 is " + 3 * 2 / 4);
System.out.println("3.0 * 2 / 4 is " + 3.0 * 2 / 4);

▼2.9.7

Write a statement to display the result of 2^3.5.

▼2.9.8

Suppose m and r are integers. Write a Java expression for mr² to obtain a floating-point result.

Section 2.10

▼2.10.1

How many accurate digits are stored in a float or double type variable?

▼2.10.2

Which of the following are correct literals for floating-point numbers?

12.3, 12.3e+2, 23.4e-2, -334.4, 20.5, 39F, 40D

▼2.10.3

Which of the following are the same as 52.534?

5.2534e+1, 0.52534e+2, 525.34e-1, 5.2534e+0

▼2.10.4

Which of the following are correct literals?

5_2534e+1, _2534, 5_2, 5_

Section 2.11

▼2.11.1

How would you write the following arithmetic expression in Java?
a.

b. 5.5 * (r + 2.5)^{2.5 + t}

Section 2.12

▼2.12.1

How do you obtain the current second, minute, and hour?

Section 2.13

▼2.13.1

Show the output of the following code:

double a = 6.5;
a += a + 1;
System.out.println(a);
a = 6;
a /= 2;
System.out.println(a);

Section 2.14

▼2.14.1

Which of these statements are true?
a. Any expression can be used as a statement.
b. The expression x++ can be used as a statement.
c. The statement x = x + 5 is also an expression.
d. The statement x = y = x = 0 is illegal.

▼2.14.2

Show the output of the following code:

int a = 6;
int b = a++;
System.out.println(a);
System.out.println(b);
a = 6;
b = ++a;
System.out.println(a);
System.out.println(b);

Section 2.15

▼2.15.1

Can different types of numeric values be used together in a computation?

▼2.15.2

What does an explicit casting from a double to an int do with the fractional part of the double value? Does casting change the variable being cast?

▼2.15.3

Show the output of the following code:

float f = 12.5F;
int i = (int)f;
System.out.println("f is " + f);
System.out.println("i is " + i);

▼2.15.4

If you change (int)(tax * 100) / 100.0 to (int)(tax * 100) / 100 in line 11 in Listing 2.8, what will be the output for the input purchase amount of 197.556?

▼2.15.5

Show the output of the following code:

double amount = 5;
System.out.println(amount / 2);
System.out.println(5 / 2);

▼2.15.6

Write an expression that rounds up a double value in variable d to an integer.

Section 2.16

▼2.16.1

How would you write the following arithmetic expression?

Section 2.17

▼2.17.1

Show the output in Listing 2.10 with the input value 1.99.

Section 2.18

▼2.18.1

Can you declare a variable as int and later redeclare it as double?

▼2.18.2

What is an integer overflow? Can floating-point operations cause overflow?

▼2.18.3

Will overflow cause a runtime error?

▼2.18.4

What is a round-off error? Can integer operations cause round-off errors? Can floating-point operations cause round-off errors?