need some help with an Array

Alex

13y2.8kJava

. 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.

10 Replies

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Vulpes13y ago
Accepted 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 < 100; 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("\n\nEven 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("\n\nOdd numbers");

for(int i = 98; i >= 0; i -= 2)
{
if ((i + 2) % 20 == 0) System.out.println();
System.out.printf("%4d", numbers[i]);
}
}
}
Alex13y ago
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....
Alex13y ago
thank u very much
Vulpes13y ago
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.
Alex13y ago
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...
Vulpes13y ago
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\n");

for(int i = 0; i < 9; i++)
{
a1[i] = i + 1;
System.out.printf("%d : %d\n", 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("\nEnter 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("\nEnter position to insert it at (0 to 9) : ");
position = Integer.parseInt(br.readLine());
if (position < 0 || 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 < position; i++) a2[i] = a1[i];

// now insert number
a2[position] = number;

// now copy remaining elements in a1 to a2
for(int i = position; i < 9; i++) a2[i + 1] = a1[i];

// print out the second array
System.out.println("\nNow, the array contains the following 10 elements\n");

for(int i = 0; i < 10; i++)
{
System.out.printf("%d : %d\n", i, a2[i]);
}
}
}
Alex13y ago
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.
Vulpes13y ago
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
Alex13y ago
Can you tell me what is it "%4d"?
Alex13y ago
Thanx a lot