java 在一位数上加零，这可能吗？
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Adding zero to a single digit number, Is it possible?
提问by steve care
public class MultiplicationTable {
public static void main (String[]a){
int[] x;
x = new int[10];
int i;
int n=0;
for (i=0;i<x.length;i++){
n++;
x[i]=n;
System.out.print(x[i] + " ");
}
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[0] * x[i] + " ");
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[1] * x[i] + " ");
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[2] * x[i] + " ");
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[3] * x[i] + " ");
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[4] * x[i] + " ");
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[5] * x[i] + " ");
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[6] * x[i] + " ");
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[7] * x[i] + " ");
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[8] * x[i] + " ");
System.out.println();
for (i=0;i<x.length;i++)
System.out.print(x[9] * x[i] + " ");
}
}
This is a program that will display a Multiplication Table like this:
这是一个将显示乘法表的程序，如下所示：
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
2 4 6 8 10 12 14 16 18 20
2 4 6 8 10 12 14 16 18 20
3 6 9 12 15 18 21 24 27 30
3 6 9 12 15 18 21 24 27 30
4 8 12 16 20 24 28 32 36 40
4 8 12 16 20 24 28 32 36 40
5 10 15 20 25 30 35 40 45 50
5 10 15 20 25 30 35 40 45 50
6 12 18 24 30 36 42 48 54 60
6 12 18 24 30 36 42 48 54 60
7 14 21 28 35 42 49 56 63 70
7 14 21 28 35 42 49 56 63 70
8 16 24 32 40 48 56 64 72 80
8 16 24 32 40 48 56 64 72 80
9 18 27 36 45 54 63 72 81 90
9 18 27 36 45 54 63 72 81 90
10 20 30 40 50 60 70 80 90 100
10 20 30 40 50 60 70 80 90 100
===============================================================
================================================== ==============
It is running and correct but I want it to look like this one:
它正在运行且正确，但我希望它看起来像这样：
01 02 03 04 05 06 07 08 09 10
01 02 03 04 05 06 07 08 09 10
01 02 03 04 05 06 07 08 09 10
01 02 03 04 05 06 07 08 09 10
02 04 06 08 10 12 14 16 18 20
02 04 06 08 10 12 14 16 18 20
03 06 09 12 15 18 21 24 27 30
03 06 09 12 15 18 21 24 27 30
04 08 12 16 20 24 28 32 36 40
04 08 12 16 20 24 28 32 36 40
05 10 15 20 25 30 35 40 45 50
05 10 15 20 25 30 35 40 45 50
06 12 18 24 30 36 42 48 54 60
06 12 18 24 30 36 42 48 54 60
07 14 21 28 35 42 49 56 63 70
07 14 21 28 35 42 49 56 63 70
08 16 24 32 40 48 56 64 72 80
08 16 24 32 40 48 56 64 72 80
09 18 27 36 45 54 63 72 81 90
09 18 27 36 45 54 63 72 81 90
10 20 30 40 50 60 70 80 90 100
10 20 30 40 50 60 70 80 90 100
===============================================
================================================
Is there any way?
有什么办法吗？
回答by Steven Luu
Yes you can! You can use String.formatto add zero padding to your output.
是的你可以！您可以使用String.format向输出添加零填充。
Example:
例子：
String.format("%05d", 2)would produce 00002.
String.format("%05d", 2)会产生00002.
Some improvement on the current code:
对当前代码的一些改进：
I'm not sure why you intend to store the numbers inside an array (for practice purpose maybe), but that is not necessary as it goes from 1 to 10 anyway. Though if you want to do that, you don't need both iand n.
我不确定您为什么打算将数字存储在数组中（可能出于实践目的），但这不是必需的，因为它从 1 到 10 无论如何。虽然如果你想这样做，你不需要i和n。
for (i=0; i<x.length; i++){
x[i] = i+1;
System.out.print(x[i] + " ");
}
Secondly, I'm sure you realize that you have a lot of duplicate code, and it's quite sequential. You can do that using 2 nested for loops, instead of having 10 single loops:
其次，我相信您已经意识到您有很多重复的代码，而且非常有顺序。您可以使用 2 个嵌套的 for 循环来做到这一点，而不是使用 10 个单循环：
for (int row = 1; row <= 10; row++) {
for (int col = 1; col <= 10; col++)
System.out.print(String.format("%03d", row * col));
System.out.println();
}
回答by dcow
Yes:
是的：
String.format("%01d", x[i]*x[j]); is what you want.
If you're familiar with printfin C then this will be familiar. If not, read the java reference on String.format format strings.
如果您熟悉printfC，那么这将是熟悉的。如果没有，请阅读有关String.format 格式字符串的 java 参考。
Also, rather than 10 System.out.printlnstatements, you can use a doubly nested loop with two counters. One to count which row you're in jand one for each column i.
此外，System.out.println您可以使用带有两个计数器的双重嵌套循环，而不是 10 个语句。一个用于计算您所在的行j，每个列一个i。
