/*
*
* To generate weather for location at longitude -98.76 and latitude 26.70 for
* the month of February do:
* java WeatherGenerator -98.76 26.70 3
*
* Remember that January is 2, February is 3 and so on.
*/
public class Main {
static final int WET = 1; // Use this value for a wet day
static final int DRY = 2; // Use this value for a dry day
// Number of days in each month, January is index 0, February is index 1
static final int[] numberOfDaysInMonth = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
/*
* Given a location (longitude, latitude) in the USA and a month of the year, the method
* returns the forecast for the month based on the drywet and wetwet transition
* probabilities tables.
*
* month will be a value between 2 and 13: 2 corresponds to January, 3 corresponds to February
* and so on. These are the column indexes of each month in the transition probabilities tables.
*
* The first day of the month has a 50% chance to be a wet day, 0-0.49 (wet), 0.50-0.99 (dry)
*
* Use StdRandom.uniform() to generate a real number uniformly in [0,1)
*
*/
public static int[] oneMonthGenerator(double longitute, double latitude,
int month, double[][] drywet, double[][] wetwet) {
// WRITE YOUR CODE HERE
int monthIndex = 12;
int days = 1;
int[][] monthArray = new int[monthIndex][days];
monthArray[0][0] = 31;
monthArray[1][0] = 28;
monthArray[2][0] = 31;
monthArray[3][0] = 30;
monthArray[4][0] = 31;
monthArray[5][0] = 30;
monthArray[6][0] = 31;
monthArray[7][0] = 31;
monthArray[8][0] = 30;
monthArray[9][0] = 31;
monthArray[10][0] = 30;
monthArray[11][0] = 31;
int arrayLen = monthArray[month-2][0];
int[] forecast = new int[arrayLen];
int randomeNum = StdRandom.uniform(0,1);
if(randomeNum < 0.5)
forecast[0] = WET;
else
forecast[0] = DRY;
for(int i = 1; i<arrayLen; i++)
{
randomeNum = StdRandom.uniform(0,1);
if(forecast[i-1] == WET)
{
if(randomeNum <= 0.45)
forecast[i] = WET;
else
forecast[i] = DRY;
}
else
{
if(randomeNum <= 0.12)
forecast[i] = WET;
else
forecast[i] = DRY;
}
}
return forecast;
}
/*
* Returns the number of mode (WET or DRY) days in forecast.
*/
public static int numberOfWetDryDays (int[] forecast, int mode) {
int count = 0;
int arrayLen = forecast.length;
for(int i =0; i<arrayLen; i++)
{
if(forecast[i] == mode)
{
count++;
}
}
return count;
}
/*
* Returns the longest number of consecutive mode (WET or DRY) days in forecast.
*/
public static int lengthOfLongestSpell (int[] forecast, int mode) {
int longest = 0;
int tempLongest = 0;
int arrayLen = forecast.length;
for(int i=0; i<arrayLen; i++)
{
if(forecast[i] == mode)
{
tempLongest++;
}
else
{
if(tempLongest > longest)
longest = tempLongest;
tempLongest = 0;
}
}
return longest;
}
/*
* Reads numberOfLocations probabilites into arrayToFill.
*
* Transition probabilities file format:
* Longitude Latitude January February March April May June July August September October November December
* -97.58 26.02 0.76 0.75 0.77 0.74 0.80 0.86 0.94 0.97 0.89 0.77 0.74 0.77
*/
public static void readTransitionProbabilities ( double[][] arrayToFill,
int numberOfLocations ) {
int row = 0;
while (row < numberOfLocations) {
arrayToFill[row][0] = StdIn.readDouble(); // Longitute
arrayToFill[row][1] = StdIn.readDouble(); // Latitude
arrayToFill[row][2] = StdIn.readDouble(); // January
arrayToFill[row][3] = StdIn.readDouble(); // February
arrayToFill[row][4] = StdIn.readDouble(); // March
arrayToFill[row][5] = StdIn.readDouble(); // April
arrayToFill[row][6] = StdIn.readDouble(); // May
arrayToFill[row][7] = StdIn.readDouble(); // June
arrayToFill[row][8] = StdIn.readDouble(); // July
arrayToFill[row][9] = StdIn.readDouble(); // August
arrayToFill[row][10] = StdIn.readDouble(); // Septmber
arrayToFill[row][11] = StdIn.readDouble(); // October
arrayToFill[row][12] = StdIn.readDouble(); // November
arrayToFill[row][13] = StdIn.readDouble(); // December
row += 1;
}
}
/*
*
* Expects files in the same directory. The first (drywet.txt) contains
* transition probabilities that reflects how often the weather changes
* from wet to dry. The second (wetwet.txt) is transition probabilities
* that reflects that the weather remains wet from one day to the next.
*
*/
public static void populateTransitionProbabilitiesArrays(double[][] drywet,
double[][] wetwet, int numberOfLocations) {
// Read transition probabilities that reflects how often the weather
// changes from wet to dry into 2D array drywet.
// The first line on the file has number of locations (lines)
StdIn.setFile("drywet.txt");
readTransitionProbabilities(drywet, numberOfLocations);
// Read transition probabilities that reflects that the weather remains
// wet from one day to the next into 2D array wetwet.
// The first line on the file has number of locations (lines)
StdIn.setFile("wetwet.txt");
readTransitionProbabilities(wetwet, numberOfLocations);
}
/*
*
* Reads the files containing the transition probabilities for US locations.
*
* To find
*
* Execution:
* java WeatherGenerator -97.58 26.02 3
*
*
*/
public static void main (String[] args) {
int numberOfRows = 4001; // Total number of locations
int numberOfColumns = 14; // Total number of 14 columns in file
// File format: longitude, latitude, 12 months of transition probabilities
// Allocate and populate arrays that hold the transition probabilities
double[][] drywet = new double[numberOfRows][numberOfColumns];
double[][] wetwet = new double[numberOfRows][numberOfColumns];
populateTransitionProbabilitiesArrays(drywet, wetwet, numberOfRows);
/*** WRITE YOUR CODE BELLOW THIS LINE. DO NOT erase any of the lines above. ***/
// Read command line inputs
double longitute = Double.parseDouble(args[0]);
double latitude = Double.parseDouble(args[1]);
int month = Integer.parseInt(args[2]);
int[] forecast = oneMonthGenerator(longitute, latitude, month, drywet, wetwet);
int drySpell = lengthOfLongestSpell(forecast, DRY);
int wetSpell = lengthOfLongestSpell(forecast, WET);
System.out.println("There are " + forecast.length + " days in the forecast for month " + month);
System.out.println(drySpell + " days of dry spell.");
System.out.println(wetSpell + " days of wet spell.");
for ( int i = 0; i < forecast.length; i++ ) {
// This is the ternary operator. (conditional) ? executed if true : executed if false
String weather = (forecast[i] == WET) ? "Wet" : "Dry";
System.out.println("Day " + (i+1) + " is forecasted to be " + weather);
}
}
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public static void main(String[] args) {
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jcenter()
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// add dependencies here as below
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Java is a very popular general-purpose programming language, it is class-based and object-oriented. Java was developed by James Gosling at Sun Microsystems ( later acquired by Oracle) the initial release of Java was in 1995. Java 17 is the latest long-term supported version (LTS). As of today, Java is the world's number one server programming language with a 12 million developer community, 5 million students studying worldwide and it's #1 choice for the cloud development.
short x = 999; // -32768 to 32767
int x = 99999; // -2147483648 to 2147483647
long x = 99999999999L; // -9223372036854775808 to 9223372036854775807
float x = 1.2;
double x = 99.99d;
byte x = 99; // -128 to 127
char x = 'A';
boolean x = true;
When ever you want to perform a set of operations based on a condition If-Else is used.
if(conditional-expression) {
// code
} else {
// code
}
Example:
int i = 10;
if(i % 2 == 0) {
System.out.println("i is even number");
} else {
System.out.println("i is odd number");
}
Switch is an alternative to If-Else-If ladder and to select one among many blocks of code.
switch(<conditional-expression>) {
case value1:
// code
break; // optional
case value2:
// code
break; // optional
...
default:
//code to be executed when all the above cases are not matched;
}
For loop is used to iterate a set of statements based on a condition. Usually for loop is preferred when number of iterations is known in advance.
for(Initialization; Condition; Increment/decrement){
//code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while(<condition>){
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (<condition>);
Class is the blueprint of an object, which is also referred as user-defined data type with variables and functions. Object is a basic unit in OOP, and is an instance of the class.
class keyword is required to create a class.
class Mobile {
public: // access specifier which specifies that accessibility of class members
string name; // string variable (attribute)
int price; // int variable (attribute)
};
Mobile m1 = new Mobile();
public class Greeting {
static void hello() {
System.out.println("Hello.. Happy learning!");
}
public static void main(String[] args) {
hello();
}
}
Collection is a group of objects which can be represented as a single unit. Collections are introduced to bring a unified common interface to all the objects.
Collection Framework was introduced since JDK 1.2 which is used to represent and manage Collections and it contains:
This framework also defines map interfaces and several classes in addition to Collections.
| Collection | Description |
|---|---|
| Set | Set is a collection of elements which can not contain duplicate values. Set is implemented in HashSets, LinkedHashSets, TreeSet etc |
| List | List is a ordered collection of elements which can have duplicates. Lists are classified into ArrayList, LinkedList, Vectors |
| Queue | FIFO approach, while instantiating Queue interface you can either choose LinkedList or PriorityQueue. |
| Deque | Deque(Double Ended Queue) is used to add or remove elements from both the ends of the Queue(both head and tail) |
| Map | Map contains key-values pairs which don't have any duplicates. Map is implemented in HashMap, TreeMap etc. |