Java Cheat Sheet, Cheat Sheet of Java Programming

Download Java Cheat Sheet and more Cheat Sheet Java Programming in PDF only on Docsity! CORE JAVA CHEATSHEET Learn JAVA from experts at https://www.edureka.co Iterative StatementsJava Programming Java is a high level, general purpose programming language that produces software for multiple platforms. It was developed by James Gosling in 1991 and released by Sun Microsystems in 1996 and is currently owned by Oracle. Arrays In Java User -Defined Exceptions // for loop for (condition) {expression} // for each loop for (int i: someArray) {} // while loop while (condition) {expression} // do while loop do {expression} while(condition) Primitive Data Types Type Size Range byte 8 -128..127 short 16 -32,768..32,767 int 32 -2,147,483,648.. 2,147,483,647 long 64 9,223,372,036,854,775,808.. 9,223.. float 32 3.4e-0.38.. 3.4e+0.38 double 64 1.7e-308.. 1.7e+308 char 16 Complete Unicode Character Set Boolean 1 True, False Java Operators Type Operators Arithmetic +, – , *, ? , % Assignment =, +=, -=, *=, /=, %=, &=, ^=, |=, <<=, >>=, >>>= Bitwise ^, &, | Logical &&, || Relational <, >, <=, >=,==, != Shift <<, >>, >>> Ternary ? : Unary ++x, –x, x++, x–, +x, –x, !, ~ {public|private} [static] type name [= expression|value]; Java Variables {public|private} [static] {type | void} name(arg1, ..., argN ){statements} Java Methods Data Type Conversion // Widening (byte<short<int<long<float<double) int i = 10; //int--> long long l = i; //automatic type conversion // Narrowing double d = 10.02; long l = (long)d; //explicit type casting // Numeric values to String String str = String.valueOf(value); // String to Numeric values int i = Integer.parseInt(str); double d = Double.parseDouble(str); User Input // Using BufferReader BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String name = reader.readLine(); // Using Scanner Scanner in = new Scanner(System.in); String s = in.nextLine(); int a = in.nextInt(); // Using Console String name = System.console().readLine(); Basic Java Program public class Demo { public static void main(String[] args) { System.out.println("Hello from edureka!"); } } Save Compile Execute className.java javac className java className for (i = 1; i <= n; ++i) { System.out.print(t1 + " + "); int sum = t1 + t2; t1 = t2; t2 = sum; } Fibonacci series k = 2*n - 2; for(i=0; i<n; i++) { for(j=0; j<k; j++){System.out.print(" ");} k = k - 1; for(j=0; j<=i; j++ ){System.out.print("* ");} System.out.println(); } Pyramid Pattern Decisive Statements //if statement if (condition) {expression} //if-else statement if (condition) {expression} else {expression} //switch statement switch (var) { case 1: expression; break; default: expression; break; } if (n < 2) { return false; } for (int i=2; i <= n/i; i++) { if (n%i == 0) return false; } return true; Prime Number // Creating String using literal String str1 = “Welcome”; // Creating String using new keyword String str2 = new String(”Edureka”); str1==str2 //compare the address; String newStr = str1.equals(str2); //compares the values String newStr = str1.equalsIgnoreCase() // newStr = str1.length() //calculates length newStr = str1.charAt(i) //extract i'th character newStr = str1.toUpperCase() //returns string in ALL CAPS newStr = str1.toLowerCase() //returns string in ALL LOWERCASE newStr = str1.replace(oldVal, newVal) //search and replace newStr = str1.trim() //trims surrounding whitespace newStr = str1.contains("value"); //Check for the values newStr = str1.toCharArray(); //Convert into character array newStr = str1.IsEmpty(); //Check for empty String newStr = str1.endsWith(); //Checks if string ends with the given suffix 1 - Dimensional // Initializing type[] varName= new type[size]; // Declaring type[] varName= new type[]{values1, value2,...}; double[] arr = new double[n]; for (int i=0; i<n; i++) {a[i] = Math.random();} Array with Random Variables double max = 0; for (int i=0; i<arr.length(); i++) { if(a[i] > max) max = a[i]; } Maximum value in an Array for(int i=0; i<(arr.length())/2; i++) { double temp = a[i]; a[i] = a[n-1-i]; a[n-1-i] = temp; } Reversing an Array // Initializing datatype[][] varName = new dataType[row][col]; // Declaring datatype[][] varName = {{value1, value2....},{value1, value2....}..}; Multi – Dimensional Arrays for(i = 0; i < row; i++) { for(j = 0; j < column; j++) { System.out.print(array[i][j]+" "); } System.out.println(" "); } Transposing A Matrix for (i = 0; i < row1; i++) { for (j = 0; j < col2; j++) { for (k = 0; k < row2; k++) { sum = sum + first[i][k]*second[k][j]; } multiply[i][j] = sum; sum = 0; } } Multiplying two Matrices Java Strings int factorial(int n) { if (n == 0) {return 1;} else { return(n * factorial(n-1)); } } Factorial of a Number String Methods