public class MyArray { public static void main(String[] args) { int[] numbers = {1,2,3,4,5,6,7,8,9,10}; // print forward for ( int i = 0; i < numbers.length; i++ ) { System.out.print(numbers[i] + " "); } System.out.println(); // print reverse order for ( int i = numbers.length-1; i >= 0 ; i--) { System.out.print(numbers[i] + " "); } System.out.println(); } }
$ java MyArray 1 2 3 4 5 6 7 8 9 10 10 9 8 7 6 5 4 3 2 1
import java.util.Scanner; public class GetVowels { public static void main(String[] args) { String vowels = "AEIOUaeiou"; System.out.print("Enter a string: "); Scanner in = new Scanner(System.in); String str = in.nextLine(); for(int i=0;i<str.length();i++){ String onechar = str.substring(i,i+1); if( vowels.indexOf(onechar) != -1){ System.out.print(onechar); } } System.out.println(); } }
$ java GetVowels Enter a string: abcDEFghi aEi
import java.util.*; public class ReadInt { public static void main(String[] args) { Scanner sc = new Scanner(System.in); while(true) { try { System.out.print("Enter Positive Number: "); int i = sc.nextInt(); if(i > 0){ System.out.println("You entered: " + i); System.out.println("Thank you"); break; } else { System.out.println("Negative Number"); } } catch (InputMismatchException e) { System.out.println("You did not enter a Number."); sc.nextLine(); } } } }
$ java ReadInt Enter Positive Number: hello You did not enter a Number. Enter Positive Number: -222 Negative Number Enter Positive Number: 100 You entered: 100 Thank you
import java.util.*; public class ReadInt { public static void main(String[] args) { Scanner sc = new Scanner(System.in); int number = 0; while (true) { try { System.out.print("Enter number betwen 1 and 10: "); number = sc.nextInt(); if( number >= 1 && number <= 10){ break; } System.out.println("Out of range."); } catch (InputMismatchException e) { System.out.println("You did not enter a Integer."); sc.nextLine(); // needed to clear buffer } } System.out.println("You entered: " + number); } }
$ java ReadInt Enter number betwen 1 and 10: 11 Out of range. Enter number betwen 1 and 10: a You did not enter a Integer. Enter number betwen 1 and 10: 12 Out of range. Enter number betwen 1 and 10: 10 You entered: 10
import java.util.*; public class LowestNumber { public static void main(String[] args) { int[] array = new int[15]; // populate array Random r = new Random(); for(int i=0;i<array.length;i++){ array[i]= r.nextInt(1000); } System.out.println("Contents: " + Arrays.toString(array)); // find smallest and largest numbers int small = array[0]; int large = array[0]; for(int i=0;i<array.length;i++){ if(array[i] <= small){ small = array[i]; } if(array[i] >= large){ large = array[i]; } } System.out.println("Smallest number: " + small); System.out.println("Largest number: " + large); } }
$ java LowestNumber Contents: [489, 283, 334, 331, 665, 643, 280, 100, 184, 642, 730, 560, 930, 517, 24] Smallest number: 24 Largest number: 930
import java.util.*; public class SSN { public static void main(String args[]){ boolean valid = false; System.out.print("Enter SSN: "); Scanner sc = new Scanner(System.in); String ssn = sc.next(); System.out.println("Input: "+ssn); if(ssn.length()==11) { if( (ssn.charAt(3)=='-') & (ssn.charAt(6)=='-') ) { String str = ssn.replaceAll("-", ""); if (str.matches("[0-9]+") & str.length()==9) { valid = true; } } } System.out.println("valid: " + valid); } }
$ java SSN Enter SSN: 123-12-1234 Input: 123-12-1234 valid: true $ java SSN Enter SSN: 123-123-123 Input: 123-123-123 valid: false $ java SSN Enter SSN: 123-12-123a Input: 123-12-123a valid: false
import java.util.*; import java.math.*; public class MakeChange { public static void main(String[] args) { Scanner sc = new Scanner(System.in); // example: 39.99 System.out.print("Enter total amount: "); double amount = sc.nextDouble(); // Multiple by 100 so all the math can handle ints int remainder = (int)(amount * 100); int twentys = remainder / 2000 ; remainder = remainder - (twentys * 2000); int tens = remainder / 1000 ; remainder = remainder - (tens * 1000); int fives = remainder / 500 ; remainder = remainder - (fives * 500); int dollars = remainder / 100 ; remainder = remainder - (dollars * 100); int quarters = remainder / 25 ; remainder = remainder - (quarters * 25); int dimes = remainder / 10 ; remainder = remainder - (dimes * 10); int nickels = remainder / 05 ; remainder = remainder - (nickels * 05); int pennies = remainder / 01 ; System.out.println("Twentys: " + twentys); System.out.println("Tens: " + tens); System.out.println("Fives: " + fives); System.out.println("Dollars: " + dollars); System.out.println("Quarters: " + quarters); System.out.println("Dimes : " + dimes); System.out.println("Nickels : " + nickels); System.out.println("Pennies : " + pennies); } }
$ java MakeChange Enter total amount: 39.99 Twentys: 1 Tens: 1 Fives: 1 Dollars: 4 Quarters: 3 Dimes : 2 Nickels : 0 Pennies : 4