嵌套循环输出打印和格式化不正确的表格，这一切都很时髦

Question

So the goal was to use a nested for loop to output 6 rows and 10 columns. The thing was though that the inner for loop was supposed to check to see whether the number was even or odd as, if it was even, we would add 2 to it and then print out that number 10 times before moving onto the next output. So this is what were were supposed to get

1 1 1 1 1 1 1 1 1 1  
4 4 4 4 4 4 4 4 4 4  
3 3 3 3 3 3 3 3 3 3   
6 6 6 6 6 6 6 6 6 6  
5 5 5 5 5 5 5 5 5 5  
8 8 8 8 8 8 8 8 8 8 

I thought I was on the right track but my output is a complete mess, here's what I have. Thank you to anyone willing to help.

for (int numberE = 1; numberE <= 6; numberE++)
{
    for (int nestedE = 1; nestedE < 10; nestedE++)
    {
        if (numberE%2 == 0)
        {
            numberE += 2;
            System.out.printf("%2d", numberE);
        }   else {
              System.out.printf("%2d", numberE);
        }
    }
    System.out.printf("%2d\n", numberE);
}

Answer 1

well to start with your inner loop will only iterate nine times. second you don't need a nested loop, you need one loop and a guard determining when to print.

Answer 2

I would suggest using a temporary variable to store the current intended value.

The issue with your solution was that you were modifying the value of numberE by using numberE += 2; inside the second for loop, this changes the value globally.

Moving the final column in to the nested for loops also makes it easier as you wouldn't need to define the temporary variable outside of the loop. Using this also meant changing the <10 to <=10 .

for (int numberE = 1; numberE <= 6; numberE++) {
   for (int nestedE = 1; nestedE <= 10; nestedE++) {
     int current = (numberE % 2 == 0) ? numberE + 2 : numberE;
     System.out.printf("%2d", current);
   }
System.out.printf("\n");
}

You were pretty close though, with practise you'll get better.

Answer 3

Don't modify numberE inside the loops. Instead just print numberE + 2.

Also, if your inner loop runs from 0 to <10 you will get 10 iterations and you don't need to print the number again - just a newline.

for (int numberE = 1; numberE <= 6; numberE++)
{
    for (int nestedE = 0; nestedE < 10; nestedE++) // <-- start at 0 and end <10 for 10 iterations
    {
        if (numberE%2 == 0)
        {
            System.out.printf("%2d", numberE + 2); // <-- print the number + 2
        } else {
            System.out.printf("%2d", numberE);
        }
    }
    System.out.println(); // <-- don't print the value again here
}

Answer 4

I would do it this way. Gives the required result.

public class NestedForLoop {

public static void main(String[] args) {
    for (int i = 1; i <= 6; i++)
    {
        int temp = i;
        if(temp%2 == 0) {
            temp +=2;
        }
        for(int j=1;j<=10;j++) {
            System.out.print(temp+" ");
        }
        System.out.println();
    }
}

}

A brief description of what is happening here: So, since we need 6 rows, we use the value of 6 as a row counter. The variable i takes care of keeping a count of the rows. Here since the target is 6, we start from row number 1 and go until row no 6. Inside each value of the loop, we save the value of i to temp because we don't want the value of i to change before incrementing in the main for loop. We then check if this temp value is even by doing a modulo division by 2. If it is even, we increment the temp value by 2.
Then, we run a loop from 1 to 10 since we need 10 columns to print the value temp(either the original i or incremented because it was even). After exiting the loop, finally to move to the next row, we do a System.out.println().