CSC 116 - Exam 1
<var>.indexOf("<string>");
Returns the first instance of the string indicated. String must be in quotation marks. Counting starts at 0 String x = "Raleigh"; System.out.println(x.indexOf("al")); output: 1
Object
A programming entity that contains states and behavior An object is an instance of a class
Declaration
A request to set aside a new variable with a given type and name int x; //this is declaring a variable
\t
Tab System.out.println("Hello\tWorld"); output: Hello World
Statement
Line of Code which contains a Declaration, Equation, or Initialization; Ends with a Semicolon An executable snippet of code that represents a complete command System.out.println("Hello World!");
Memory Address
Name for a main memory cell which can contain a byte of data
Identifier
Name used to identify and reference to Class, Method, and Variables int x = 2; x is the identifier.
printf
format strings int x = 3; int y = -17; System.out.printf("x is %d and y is %d!\n", x, y); // x is 3 and y is -17!
Math.toDegrees Math.toRadians
converts to degrees from radians and vice versa
Math.max
larger of two values
<=
less than or equal to
Math.floor
rounds down
Math.round
rounds to the nearest whole number
Math.ceil
rounds up
\\
Include backslash System.out.println("\\Hello World\\"); output: \Hello World\
\"
Include the double quotes in the string System.out.println("He said, \"Hello\""); output: He said, "Hello"
++
Increment Operator which increases the variable by 1
Math.abs
absolute value
byte short long float
1 byte 2 bytes 8 bytes 4 bytes
for loops
1. initialization 2. continuation test 3. update 4. body for (int i = 0; i < 5; i++){
Class Constants
A fixed value visible to the whole program. Allows for multiple methods to access the constant Must be written in a different way: public static final int x = 5;
Variable
A memory location with a name and a type that stores a value
String
A sequence of characters enclosed in double-quotes String str = new String("Hello World"); String str = "Hello World";
Expression
A simple value or a set of operations that produces a value
Algorithm
A step-by-step description of how to accomplish a task Sequence of steps Repetitive (Loops) Decisions (If-else)
Index
An integer used to specify a location in a sequence of values. Indexes are zero based so the first character in a string is 0!
+=
Augmented operator which performs Mathematical Addition on Numbers or Concatenation on Strings and Stores the value into the original variable
/=
Augmented operator which performs Mathematical Division and Stores the value into the original variable
%=
Augmented operator which performs Mathematical Modulus (Remainder) and Stores the value into the original variable
*=
Augmented operator which performs Mathematical Multiplication and Stores the value into the original variable
-=
Augmented operator which performs Mathematical Subtraction and Stores the value into the original variable
Bit
Binary Digit
Procedural Decomposition
Breaking down a problem into simpler parts by using methods that do a certain task. This is useful for doing repetitive tasks.
Logical Error
Bug in a program that allows the program to run but does not give the output that it needs error in algorithm
System.in
Class and Variable which is used to collect information from the Keyboard; Used in conjunction with "Scanner" method Scanner sc = new Scanner(System.in);
System.out
Class and Variable which is used to send information to the Screen; Provokes "Println" and "Print" System.out.println(); System.out.print();
Casting
Convert a data type to a different data type int k = 5; double p = (double) k;
Numeric Literals
Constant value which appears directly in a program as a digit; Integer Literals can be stored as Long by adding "L"; Double Literals can be stored as Float by adding "F"
Method (Function)
Construct which contains the statements within a program A program unit that represents a particular action or computation Two types ○ Static methods ○ Class methods
--
Decrement Operator which decreases the variable by 1
Class Method Instance Method
Dependent on the class s.length(); Scanner scr = new Scanner(System.in);
Class
Division of a Java Program, of which all programs must have at least one; Contains specific items called "objects" A unit of code that is the basic building block of Java programs. ● Every program in Java is a "class" Two types of programming ○ Procedural (like a recipe) ○ Object-oriented
void method
Does not return a value to the method call public static void <name> (){
Runtime Error
Error that occurs while the program is running spelling "main" wrong divide by 0
import java.util.Scanner;
Explicit Statement to import Scanner Class
<var>.substring(<index>, <index+1>)
Extracts a portion of the string from the given starting index and 1 plus the ending index
nextDouble()
Function used to collect the next Double input from the keyboard
nextFloat()
Function used to collect the next Float input from the keyboard
nextInt()
Function used to collect the next Integer input from the keyboard
nextLong()
Function used to collect the next Long input from the keyboard
nextShort()
Function used to collect the next Short input from the keyboard
Initialization
Giving a value to a variable at the same time that it is "declared" int x = 7;
Named Constants
Identifier which represents a variable storing a permanent value; Declaration must be preceded by "final"
import java.util.*;
Implicit Statement to import Scanner Class
Static Method
Independent of Class public static void getAverage(){ public static double average() { double x = 7.0; return x;
Scanner input = new Scanner(System.in);
Initialization Statement for new Scanner Instance
Translator
Interpreter which converts and runs one line of code at a time
Compiler
Interpreter which converts entire file at once javac HelloWorld.java
!=
Is not equal?
Programming Language
Languages understood by the computer; Used to create Computer programs, or software
Integer Division
Mathematical division which returns only the Whole number and truncates the Decimal
Floating Point Division
Mathematical division which returns the Whole number and the Decimal; Requires one Operator to be a Floating Point
Byte
Measurement of 8 bits
\n
New line System.out.println("Hello \nWorld"); output: Hello World
+ (Addition)
Operator which performs Mathematical Addition on Numbers and Concatenation on Strings
% (Remainder or Modulus)
Operator which returns the Remainder from performing Division on Numbers
=
Operator which stores the value on the right into the variable on the left
Java Virtual Machine
Program which executes Java Bytecode (i.e., code w/ .class extension)
Interpreter
Programming Tool which converts programs into binary code
Low- level Language
Programming language that is understood by the computer but not by the reader.
High-Level Language
Programming language which uses a series of statements to create programs; Uses language similar to English. Can be read by the reader but not the computer
return method
Returns a value to the method call. public static <type> <name>() { return x; }
Class Block
Section of code which is associated with a particular Class name
Method block
Section of code which is associated with a particular Method name
Comment
Section of code which is ignored by the Compiler; Used to leave messages to the programmer // or /**/
double <var> = <value>;
Stores a decimal value 8 bytes
int <var> = <value>;
Stores a whole number only 4 bytes
char <var> = '<string>'
Stores one character enclosed in single quotes char hello = 'h'; System.out.print(hello); output: h
>
Strictly greater than
<
Strictly less than
Syntax Error
The Java program is not able to read the code because of improper grammar. Caught by the compiler
Method Overloading
The ability to define two or more different methods with the same name but different method signatures
Evaluation
The process of obtaining the value of an expression
Escape sequences
Used to show things in double quotes such as quotation marks, backslash, new line, tab. Will be added before \
Parameter Argument
Value that is "passed" to and used by a method
Return Value
Value that is passed back from a method to the method call
Data Type Keyword Reserved words
Variable declarative which denotes the Type and Amount of storable Data Words that are reserved for use by Java as having special meaning and purpose ex. public, static, void, class int x = 2; int is the data type or the keyword
Constants
Variables whose value the program cannot change ● Naming convention: All caps with underscores final int ALL_CAPS_WITH_UNDERSCORES = 5;
System.out.println();
Will print the string inside the parenthesis and then go to the next line
Math.pow
base to the exp power
Math.E
e value (2.718)
>=
greater that or equal to
Nested for loops
i is the rows j is the columns
Scanner class
import java.util.*; Scanner console = new Scanner(System.in);
%d
integer
==
is equal? boolean y = 5 == 4; System.out.println(y); output: false
Math.log10
logarithm, base 10
<var>.toUpperCase <var>.toLowerCase
makes everything uppercase makes everything lowercase
Math.random
picks a double between 0 and 1 multiply by max number to get a number between 1 and max
%f
real number
<var>.charAt(<index>);
returns the character at that particular index. Starts counting at 0. String c = "Raleigh"; System.out.print(c.charAt(1)); output: a
<variablename>.length();
returns the length of the string. Starts counting at 1. String str = new String("Hello World"); System.out.println(str.length()); output: 11
Math.sin Math.cos Math.tan
sine/cosine/tangent of an angle in radians
Math.min
smaller of two values
Math.sqrt
square root
%s
string
boolean
true or false statement for (int x = 0; x < 0; x++){} //x < 0 is boolean