Question: Topics: About Java What is a compiler, and what does it do? Characteristics of the languageStrongly typed and statically typed Everything has a data type
Topics:
About Java
What is a compiler, and what does it do?
Characteristics of the languageStrongly typed and statically typed
Everything has a data type & data types must be declared
Case sensitive
Object oriented
System.out.print() vs. System.out.println()
How to use the Scanner class to obtain user input
Data typesWhat are they?
Know the basic types like: int, double, boolean, String, etc.
Variables
What is a variable?
Declarations
Initialization
Assignment
Constants
Reserved words like:
What is a reserved word?
Examples: class, if, import, static, void, while, etc.
Comments what are they and why do we use them?
Strings
String literals
Concatenation
Escape sequences
String methods:
charAt()
equals()
indexOf()
length()
substring()
toLowerCase() & toUpperCase()
Operators
Arithmetic: +, -, *, /, %
Relational: >, >=, <, <=, ==, !=
Boolean: !, &&, ||
Evaluating expressions
Arithmetic
Relational
Boolean
Decision logic structures using if and if/else statements
Be able to read simple code with if statements and evaluate the output
Be able to write simple programs of no more than 10 lines of code.
Looping structures using while, do/while, and for
Be able to read simple code with loops and evaluate the output
Be able to write simple programs of no more than 10 lines of code.
// Some example code that demonstrates many of the topics listed above
import java.util.Scanner;
public class TestCode
{
public static void main(String []args)
{
Scanner in = new Scanner(System.in);
String text = "";
int spaceCount = 0;
int wordCount = 0;
int letterCount = 0;
double averageWordLength = 0.0;
boolean inputIsValid = false;
boolean hasNoSpaces = false;
boolean startsWithSpace = false;
boolean endsWithSpace = false;
final char SPACE = ' ';
do // get a string of words from the user
{
hasNoSpaces = false;
startsWithSpace = false;
endsWithSpace = false;
System.out.print("Enter some words separated by spaces: ");
text = in.nextLine();
// if the text the user enters has no spaces
// then it cannot have more than one word.
if (text.indexOf(SPACE) == -1)
hasNoSpaces = true;
// if the text the user enters starts with a space
// then it is wrong.
if (text.substring(0, 1).equals(" "))
startsWithSpace = true;
// if the text the user enters ends with a space
// then it is wrong.
if (text.substring(text.length() - 1).equals(" "))
endsWithSpace = true;
} while (hasNoSpaces || startsWithSpace || endsWithSpace);
// count the spaces
// by looping through the character in the string index by index
for (int index = 0; index < text.length(); index++)
{
if (text.charAt(index) == SPACE)
spaceCount += 1;
}
// count the words
wordCount = spaceCount + 1; // there will be one more word than spaces
System.out.println("There are " + wordCount + " words in \"" + text + "\" ");
// find the average word length
letterCount = text.length() - spaceCount;
averageWordLength = (double)letterCount / wordCount; // average letters per word
System.out.println("There average word length is:\t\t" + averageWordLength + " ");
// get the first word and capitalize it
int indexOfFirstSpace = text.indexOf(SPACE);
String firstWord = text.substring(0, indexOfFirstSpace);
firstWord = firstWord.toUpperCase();
System.out.println("The first word in upper case is:\t" + firstWord + " ");
// get the last word and capitalize it
int indexOfLastSpace = text.lastIndexOf(SPACE);
String lastWord = text.substring(indexOfLastSpace + 1);
lastWord = lastWord.toUpperCase();
System.out.println("The last word in upper case is:\t\t" + lastWord + " ");
// which word is longer - the first word or the last word?
if (firstWord.length() > lastWord.length())
{
System.out.printf("\"%s\" is longer than \"%s\".", firstWord, lastWord);
}
else if (firstWord.length() < lastWord.length())
{
System.out.printf("\"%s\" is shorter than \"%s\".", firstWord, lastWord);
}
else
{
System.out.printf("\"%s\" and \"%s\" are the same length.",
firstWord, lastWord);
}
}
}
You will be given the following information on the exam document:
Quick Reference:
class java.lang.String
char charAt(int index) // Returns the character at the specified index.
int compareTo(String anotherString) // Compares two string lexicographically.
int length( ) //Returns the length of this string.
String substring(int from , int to ) //Returns a new string that is a substring of this string.
String substring(int from) //Returns substring(from, length())
String toLowerCase( )
int indexOf(String s) // returns the index of the first occurrence of s, returns 1 if not found
class java.util.Scanner
String next() // reads the next string token from the keyboard
String nextLine() // returns all input remaining on the current line as a string
double nextDouble()
int nextInt()
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