need some help with an Array

Question

. Set up an array of 100 integers – starting from 1. Print out your array in reverse order. Display 10 numbers per line. Use printf to help with the output. Output a list of even numbers. Output a list of odd numbers.

Vulpes · Answer

Try this: import java.io.*; class DisplayNumbers { public static void main(String[] args) { int[] numbers = new int[100]; // initialize array for(int i = 0; i { numbers[i] = i + 1; } // print all numbers System.out.println("All numbers"); for(int i = 99; i >= 0; i--) { if ((i + 1) % 10 == 0) System.out.println(); System.out.printf("%4d", numbers[i]); } // print even numbers System.out.println("

Even numbers"); for(int i = 99; i >= 1; i -= 2) { if ((i + 1) % 20 == 0) System.out.println(); System.out.printf("%4d", numbers[i]); } // print odd numbers System.out.println("

Odd numbers"); for(int i = 98; i >= 0; i -= 2) { if ((i + 2) % 20 == 0) System.out.println(); System.out.printf("%4d", numbers[i]); } } }

Vulpes · Answer

You can set the default fields to anything you like but, apart from the country where I've used Kazakhstan, I've just used empty strings for the rest.

Vulpes · Answer

Sure, try this: import java.io.*; class ArrayInsertion { public static void main(String[] args) throws IOException { // create 2 array with 9 and 10 elements respectively int[] a1 = new int[9]; int[] a2 = new int[10]; // populate the first array with the numbers 1 to 9 say and print it out System.out.println("Initially, the array contains the following 9 elements
"); for(int i = 0; i { a1[i] = i + 1; System.out.printf("%d : %d
", i, a1[i]); } // get number to insert and position to insert it at int number = 0; BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); Boolean isValid; do { isValid = true; try { System.out.print("
Enter number to insert : "); number = Integer.parseInt(br.readLine()); } catch (NumberFormatException e) { System.out.println("Not a valid integer, try again"); isValid = false; } } while(!isValid); int position = 0; do { isValid = true; try { System.out.print("
Enter position to insert it at (0 to 9) : "); position = Integer.parseInt(br.readLine()); if (position 9) { System.out.println("Must be between 0 and 9 inclusive, try again"); isValid = false; } } catch (NumberFormatException e) { System.out.println("Not a valid integer, try again"); isValid = false; } } while(!isValid); // copy elements before insertion point from a1 to a2 for(int i = 0; i // now insert number a2[position] = number; // now copy remaining elements in a1 to a2 for(int i = position; i // print out the second array System.out.println("
Now, the array contains the following 10 elements
"); for(int i = 0; i { System.out.printf("%d : %d
", i, a2[i]); } } }

Vulpes · Answer

It's a numeric format string which you can use with printf. It means format an integer in a field which is 4 characters long. If the integer has less than 4 digits, the field will be padded out with spaces to the left. So, here, we have integers varying in length from 1 to 3 characters. If we use a field size of 4 that will ensure there's at least one space between each integer when we print them to the console. There's a useful article here on formatting strings with Java: http://www.homeandlearn.co.uk/java/java_formatted_strings.html

Alex · Answer

Can you tell me what is it "%4d"?

Alex · Answer

Hello. Can i ask again your help? I created a calcWeeksPay method which is counting payment or overtime payments if more than 40hours. But i have a problem because in formula i have 2 different types double and int and i have incorrect result. Sorry for bothering you....

Alex · Answer

thank u very much

Alex · Answer

hello! pls can you help me with my assignment... i started and can't finish it. i have so many mistakes, java is very confusing me..... need really you help...

Alex · Answer

Can you help me with one more programm pls? 1. Write a program that will allow the user to insert a number supplied by the user into a position also supplied by the user into an integer array of max size 10. Normal 0 false false false EN-AU ZH-CN AR-SA /* Style Definitions */ table.MsoNormalTable{mso-style-name:"Table Normal";mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-priority:99;mso-style-parent:"";mso-padding-alt:0cm 5.4pt 0cm 5.4pt;mso-para-margin:0cm;mso-para-margin-bottom:.0001pt;mso-pagination:widow-orphan;font-size:10.0pt;font-family:"Times New Roman","serif";}

Alex · Answer

Thanx a lot

need some help with an Array

Answers (10)