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Java provides simple data types for representing integers, real numbers, characters, and Boolean types. These types are known as _ or fundamental types.

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primitive data types

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Java provides simple data types for representing integers, real numbers, characters, and Boolean types. These types are known as primitive data types or _.

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fundamental types

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Real numbers (i.e., numbers with a decimal point) are represented using a method known as _ in computers.

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floating-point

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So, the real numbers are also called _

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floating-point numbers

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The _ word _ indicates that radius and area are floating-point values stored in the computer.

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reserved, double

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The method of reviewing how a program works is called _; helpful for understanding how programs work, and they are useful tools for finding errors in programs.

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tracing a program

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The plus sign (+) has two meanings: one for addition and the other for concatenating (combining) strings. The plus sign for concatenating is called a _.

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string concatenation operator

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Java uses System.out to refer to the standard output device and System.in to the standard input device. By default, the output device is the display monitor and the input device is the _.

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keyboard

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The syntax _ creates an object of the Scanner type. The syntax Scanner input declares that input is a variable whose type is Scanner.

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new Scanner(System.in)

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The syntax __ declares that input is a variable whose type is Scanner.

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Scanner input

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An object may invoke its methods. To invoke a method on an object is to ask the object to _.

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perform a task

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This statement reads a number from the keyboard and assigns the number to radius.

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double radius = input.nextDouble();

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Console input is not directly supported in Java, but you can use the Scanner class to create an object to read input from System.in, as follows:

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Scanner input = new Scanner(System.in);

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Import the class Scanner (use the code instruction)

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import java.util.Scanner;

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System.out.print("Enter a number for radius: "); Now enter the code to except user Radius entry:

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double radius = input.nextDouble();

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System.out.print("Enter a number for radius: ") is known as a _

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prompt

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_ moves to the beginning of the next line after displaying the string, but _ does not advance to the next line when completed.

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println, print

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The Scanner class is in the __.

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java.util package

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There are two types of import statements: _ import and _ import

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specific, wildcard

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The specific import specifies _ in the import statement.

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a single class

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The _ import imports all the classes in a package by using the asterisk as the wildcard.

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wildcard

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For example, the following statement imports all the classes from the package java.util.

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import java.util.*;

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The information for the classes in an imported package is not read in at compile time or runtime unless the class is used in the program. The import statement simply tells the compiler where to locate the classes. There is _ between a specific import and a wildcard import declaration.

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no performance difference

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Line 9 prompts the user to enter three numbers. The numbers are read in lines 10-12. You may enter three numbers _, then press the Enter key, or enter each number followed by a press of the Enter key, as shown in the sample runs of this program.

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separated by spaces

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An identifier must start with a letter, an underscore (_), or _. It cannot start with _.

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$, a digit

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An identifier cannot be a _

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reserved word

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An identifier cannot be true, false, or _.

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null

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An identifier _ be of any length.

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can

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An _ is a sequence of characters that consists of letters, digits, underscores (_), and dollar signs ($).

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identifier

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Identifiers are the names that identify the elements such as _, and variables in a program.

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classes, methods

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$2, ComputeArea, area, radius, and print, 2A and d+4. Which would be detected by the compiler as illegal identifiers?

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2A, d+4

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area, Area, and AREA are all _.

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different identifiers (Java is case sensitive)

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By convention, the _ character should be used only in mechanically generated source code

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$

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The _ tells the compiler to allocate appropriate memory space for the variable based on its data type.

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variable declaration

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The syntax for declaring a variable is __

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datatype variableName;

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Declare count to be an integer variable

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int count;

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Declare radius to be a double variable

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double radius;

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Declare interestRate to be a double variable

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double interestRate;

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Declare i, j, and k as int variables on one line

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int i, j, k;

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draw with one line: int count; count = 1;

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int count = 1;

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draw with one line: int i = 1, int j = 2;

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int i = 1, j = 2;

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Every variable has a _; the part of the program where the variable can be referenced.

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scope

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After a variable is declared, you can assign a value to it by using an __.

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assignment statement

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In Java, the equal sign =() is used as the __.

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assignment operator

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The syntax for assignment statements is as follows:

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variable = expression;

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An _ represents a computation involving values, variables, and operators that, taking them together, evaluates to a value

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expression

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In mathematics, x = 2 * x + 1 denotes an equation. However, in Java, x = 2 * x + 1 is an __ that evaluates the expression 2 * x + 1 and _ the result to x.

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assignment statement, assigns

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In Java, an assignment statement is essentially an expression that evaluates to the value to be assigned to the variable on the left side of the assignment operator. For this reason, an assignment statement is also known as an _.

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assignment expression

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A _ is an identifier that represents a permanent value.

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named constant

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syntax for declaring a constant

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final datatype CONSTANTNAME = value;

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The word _ is a Java keyword for declaring a constant.

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final

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Declare a constant for pi 3.14

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final double PI = 3.14; (remember capitals)

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name variables and methods, naming convention

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lowercase

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class name, naming convention

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Capitalized

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constants, naming convention

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CAPITALIZED

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Java provides _ primitive data types for numeric values, characters, and Boolean values.

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8

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IEEE 754 is a standard approved by the _ for representing floating-point numbers on computers.

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Institute of Electrical and Electronics Engineers

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Java uses the _-bit for the float type and _-bit for the double type.

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32, 64

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Java uses the 32-bit IEEE 754 for the _ type and the 64-bit IEEE 754 for the _ type.

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float, double

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Java uses four types for integers:

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byte, int, long, short

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Java uses two types for floating-point numbers: float and double. The double type is twice as big as float, so the double is known as _ and float as single precision. Normally, you should use the _ type, because it is more accurate.

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double precision, double

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reads an integer of the byte type.

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nextByte()

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reads an integer of the short type.

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nextShort()

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reads an integer of the int type

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nextInt()

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reads an integer of the long type.

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nextLong()

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reads a number of the float type.

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nextFloat()

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reads a number of the double type.

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nextDouble()

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Scanner input = new Scanner(System.in); System.out.print("Enter a byte value: "); ????

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byte byteValue = input.nextByte();

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When both operands of a division are integers, the result of the division is the _ and the fractional part is truncated. For example, 5 / 2 yields 2, not 2.5.

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quotient, 2

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To perform a float-point division, one of the operands must be a _. For example, 5.0 / 2 yields 2.5.

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floating-point number

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The % operator, known as _ or _ operator

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remainder, modulo

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3 % 7 yields

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3

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-7 % 3 yields

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-1

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-26 % -8 yields

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-2

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20 % -13 yields

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7

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The operand on the left is the _and the operand on the right is the _. Therefore, 7 % 3 yields 1

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dividend, divisor

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Remainder is very useful in programming. For example, an even number _ is always 0 and an odd number _ is always 1. Thus, you can use this property to determine whether a number is even or odd.

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% 2

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has only one operand; has two.

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unary operator, binary operator

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- operator in -5 is a _ operator to negate number 5, whereas the - operator in 4 - 5 is a _ operator for subtracting 5 from 4.

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unary, binary

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The _ method can be used to compute a**b. The pow method is defined in the __ in the Java API.

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Math.pow(a, b), Math class

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Here, a and b are _ for the _ method and the numbers 2 and 3 are actual values used to invoke the method. For example, System.out.println(Math.pow(2, 3)); // Displays _

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parameters, pow, 8.0

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

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byte, double

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If today is Saturday, it will be Saturday again in 7 days. Suppose you and your friends are going to meet in 10 days. What day is in 10 days? You can find that the day is Tuesday using the following expression:

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(6 + 10) % 7 is 2 (Day 2 in a week is Tuesday, Day 0 is Sunday; Day 6 in a week is Saturday; a week has 7 days)

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A _ is a constant value that appears directly in a program.

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literal

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A float value has _ number of significant digits and a double value has _ number of significant digits.

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7-8, 15-17

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Floating-point literals are written with __.

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a decimal point

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Floating-point literals are written with a decimal point. By default, a floating-point literal is treated as a __ type value, not a _ type value.

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double, float

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You can make a number a float by appending the letter _, and you can make a number a double by appending the letter _.

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f/F, d/D

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The _ type values are more accurate than the _ type values (float or double)

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double, float

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Integer Literals: The statement byte b = 128, for example, will cause a compile error, because the range for a byte value is from _.

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-128 to 127

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An integer literal is assumed to be of the int type, whose value is between -231 (-2147483648) and 231 - 1 (2147483647). To denote an integer literal of the long type, append the letter _ to it.

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L/l

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By default, an integer literal is a __

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decimal integer number

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By default, an integer literal is a decimal integer number. To denote a binary integer literal, use a leading _.

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0B (/ob (zero B))

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34 and 0.305 are _ in the following statements: int numberOfYears = 34; double weight = 0.305;

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literals (numeric literals)

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Floating-point literals can be written in scientific notation in the form of _

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a * 10**b

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A special syntax is used to write scientific notation numbers. For example, 1.23456 * 10**2 is written as _ or 1.23456E+2 and 1.23456 * 10-2 as 1.23456E-2. E (or e) represents an exponent and can be in either lowercase or uppercase.

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1.23456E2

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A special syntax is used to write scientific notation numbers. For example, 1.23456 * 10**2 is written as 1.23456E2 or 1.23456E+2 and 1.23456 * 10**-2 as _. E (or e) represents an exponent and can be in either lowercase or uppercase.

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1.23456E-2

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To improve readability, Java allows you to use underscores between two digits in a _. For example, the following literals are correct. However, 45_ or _45 is incorrect. The underscore must be placed between two digits.

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number literal

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Be careful when applying division. Division of two integers yields an integer in Java. 5/9 is translated to _ instead of 5 / 9 in line 11, because 5 / 9 yields 0 in Java.

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5.0 / 9

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You can invoke _ to return the current time.

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System.currentTimeMillis()

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The currentTimeMillis method in the System class returns the current time in milliseconds elapsed since midnight, January 1, _ GMT

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1970

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The currentTimeMillis method in the System class returns the current time in milliseconds elapsed since midnight, January 1, 1970 GMT, as shown in Figure 2.2. This time is known as the _; the point when time starts, and 1970 was the year when the UNIX operating system was formally introduced.

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UNIX epoch

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// Obtain the total milliseconds since midnight, Jan 1, 1970

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long totalMilliseconds = System.currentTimeMillis();

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// Obtain the total seconds since midnight, Jan 1, 1970

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long totalSeconds = totalMilliseconds / 1000;

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// Compute the current second in the minute in the hour

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long currentSecond = totalSeconds % 60;

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// Obtain the total minutes

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long totalMinutes = totalSeconds / 60;

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// Compute the current minute in the hour

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long currentMinute = totalMinutes % 60;

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// Obtain the total hours

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long totalHours = totalMinutes / 60;

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// Compute the current hour

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long currentHour = totalHours % 24;

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// Display results (time)

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System.out.println(time); (longer string than this just an example)

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The operators +, -, *, /, and % can be combined with the assignment operator to form _.

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augmented operators

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The += is called the _. count += 1; count = count + 1;

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addition assignment operator

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-=

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Subtraction assignment

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*=

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Multiplication assignment

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Division assignment

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/=

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%=

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Remainder assignment (There are no spaces in the augmented assignment operators.)

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The augmented assignment operator is __ after all the other operators in the expression are evaluated. x /= 4 + 5.5 * 1.5; is same as x = x / (4 + 5.5 * 1.5);

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performed last

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The _ operator (++) and _ operator (- -) are for incrementing and decrementing a variable by 1.

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increment, decrement

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i = 3 i++; // i becomes _

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4

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i++ is pronounced as i __ and i-- as i _

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plus plus, minus minus

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i++ is pronounced as i plus plus and i—— as i minus minus. These operators are known as _ (or postincrement) and _ (or postdecrement), because the operators ++ and -- are placed after the variable.

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postfix increment, postfix decrement

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++i & --j: These operators are known as _ (or preincrement) and _ (or predecrement).

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prefix increment, prefix decrement

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int j = ++i; (assume i = 1) // j is _, i is _

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2, 2 (Increment var by 1, and use the new var value in the statement)

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int j = i++; (assume i =1) // j is _, i is _

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1, 2 (Increment var by 1, but use the original var value in the statement)

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int j = --i; (assume i = 1) // j is _, i is _

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0, 0

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int j = i--; // j is _, i is _ assume i = 1

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1, 0

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int i = 10; int newNum = 10 * i++; System.out.print("i is " + i + ", newNum is " + newNum); i is _, newNum is _

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11, 100 (In this case, i is incremented by 1, then the old value of i is used in the multiplication. So newNum becomes 100.)

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int newNum = 10 * i; i = i + 1; write with postfix

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int newNum = 10 * i++;

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i = i + 1; int newNum = 10 * i; write with pre-fix

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int newNum = 10 * (++i);

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int i = 10; int newNum = 10 * (++i); System.out.print("i is " + i + ", newNum is " + newNum); i is _ newNum is _

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11, 110 (i is incremented by 1, and the new value of i is used in the multiplication. Thus newNum becomes 110.)

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double x = 1.0; double y = 5.0; double z = x-- + (++y); After all three lines are executed, y becomes _, z becomes _, and x becomes _.

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6.0, 7.0, 0.0.

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Floating-point numbers can be converted into integers using _.

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explicit casting

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If an integer and a floating-point number are involved in a binary operation, Java automatically converts the integer to a _

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Floating point value (so, 3 * 4.5 is same as 3.0 * 4.5)

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You can always assign a value to a numeric variable whose type supports a larger range of values; thus, for instance, you can assign a long value to a float variable. You cannot, however, assign a value to a variable of a type with a smaller range unless you use _

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type casting

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_ is an operation that converts a value of one data type into a value of another data type.

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Casting

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Casting a type with a small range to a type with a larger range is known as _

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widening a type

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Casting a type with a large range to a type with a smaller range is known as _.

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narrowing a type (Java will automatically widen a type, but you must narrow a type explicitly)

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System.out.println((int)1.7); displays _

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1

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When a double value is cast into an int value, the fractional part is truncated. System.out.println((double)1 / 2); displays

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0.5 (because 1 is cast to 1.0 first, then 1.0 is divided by 2)

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System.out.println(1 / 2); displays

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0 (because 1 and 2 are both integers and the resulting value should also be an integer)

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Casting is necessary if you are assigning a value to a variable of a _ type range, such as assigning a double value to an int variable. A _ error will occur if casting is not used in situations of this kind.

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smaller, compile (However, be careful when using casting, as loss of information might lead to inaccurate results)

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double d = 4.5; int i = (int)d; what is i? what is d worth?

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4, 4.5 (Casting does not change the variable being cast. For example, d is not changed)

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int sum = 0; sum += 4.5 sum becomes _ after this statement

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4

question

int sum = 0; sum += 4.5 in one line, "sum = .... + ..."

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sum = (int)(sum + 4.5)

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tax * 100 is 1185.3 (int)(tax * 100) is _

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1185

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System.in is the standard input device, connected to the keyboard by default. You will be accessing it through methods of a _

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scanner object

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System.out is the standard output device, connected to the console by _. You have been using its print and println methods for display.

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by default

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A primitive data type is one that is _ to a language. A primitive data type has _-component values as opposed to object types, to be treated later in this subject, which normally have multi-component values. A single-component value is stored in a single location in memory, and that location is associated with an identifier.

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built-in, single

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The Java primitive data types consist of the _ data types (Liang section 2.9), the _data type (Liang section 4.3) and the _ data type (Liang section 3.2).

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numeric, character, boolean

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You don't need to remember the details of range and storage size, which you might use for reference. You do need to remember the ordering of the integer data types, with respect to range (_ ; _ ; _ ; _ ) and the ordering of the floating-point types with respect to both precision and range (;, ;).

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byte short int long, float double (basil fauldy)

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Note that both the addition of 1 to the maximum integer value and the subtraction of 1 from the minimum integer value are said to be cases of _. The condition of underflow arises only with floating-point calculations and will not be of concern to us in this subject.

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overflow

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char ch1 = 'A'; System.out.println(ch1 + " + 4 is " + (char)(ch1 + 4)); displays

answer

A + 4 is E

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