如何格式化打印双打 [英] How to format the printing of doubles
问题描述
例如
1 - > 1.00
0.5 - > 0.50
0.333 ... - > 0.33
DecimalFormat df = new DecimalFormat(#。##);
System.out.println(1 2 3 4 5 6 7 8 9 10);
for(double i = 1; i <= 10; i ++){
System.out.print(df.format(i)+);
if(i <10)System.out.print();
else System.out.print();
for(double j = 1; j <= 10; j ++){
double div =(j / i);
System.out.print(df.format(div));
if(div <10)System.out.print();
}
System.out.println();
打印
1 2 3 4 5 6 7 8 9 10
1 1 2 3 4 5 6 7 8 9 10
2 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
3 0.33 0.67 1 1.33 1.67 2 2.33 2.67 3 3.33
4 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5
5 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
6 0.17 0.33 0.5 0.67 0.83 1 1.17 1.33 1.5 1.67
7 0.14 0.29 0.43 0.57 0.71 0.86 1 1.14 1.29 1.43
8 0.12 0.25 0.38 0.5 0.62 0.75 0.88 1 1.12 1.25
9 0.11 0.22 0.33 0.44 0.56 0.67 0.78 0.89 1 1.11
10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
i希望将所有内容以x.xx或整齐的方式列印出来
1 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0
2 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00
3 0.33 0.67 1.00 1.33 1.6 7 2.00 2.33 2.67 3.00 3.33
etc
很多方法,但一个是使用 String.format(%。2f,myDouble)
另一种方法是使用DecimalFormat,如 DecimalFormat格式= new DecimalFormat(#0.00)
然后像 format.format(myDouble)
要格式化一个表格,可以使用 String.format(...)
或者其中一个变种printf。
$ p
pre $ $ $ $ $ $ $ $ $私有静态最终int COLS = 10;
private static final int ROWS = 10;
public static void main(String [] args){
System.out.printf(%2s,);
for(int i = 0; i< COLS; i ++){
System.out.printf(%8d,(i + 1));
}
System.out.println();
for(int i = 0; i
System.out.printf(%2d,row);
for(int j = 0; j
System.out.printf(%8.2f,myDouble);
}
System.out.println();
$ b $ / code $ / pre
打印出来
1 2 3 4 5 6 7 8 9 10
1 1.00 0.50 0.33 0.25 0.20 0.17 0.14 0.13 0.11 0.10
2 2.00 1.00 0.67 0.50 0.40 0.33 0.29 0.25 0.22 0.20
3 3.00 1.50 1.00 0.75 0.60 0.50 0.43 0.38 0.33 0.30
4 4.00 2.00 1.33 1.00 0.80 0.67 0.57 0.50 0.44 0.40
5 5.00 2.50 1.67 1.25 1.00 0.83 0.71 0.63 0.56 0.50
6 6.00 3.00 2.00 1.50 1.20 1.00 0.86 0.75 0.67 0.60
7 7.00 3.50 2.33 1.75 1.40 1.17 1.00 0.88 0.78 0.70
8 8.00 4.00 2.67 2.00 1.60 1.33 1.14 1.00 0.89 0.80
9 9.00 4.50 3.00 2.25 1.80 1.50 1.29 1.13 1.00 0.90
10 10.00 5.00 3.33 2.50 2.00 1.67 1.43 1.25 1.11 1.00
Im making a division table from 1-10 an the results range from integers to x.x to x.xx i used decimalformat to keep the the numbers to 2 decimal places but that throws off the format of the table. How would i print the numbers so that they would all be x.xx
for example
1 -> 1.00
0.5 -> 0.50
0.333... -> 0.33
DecimalFormat df = new DecimalFormat("#.##");
System.out.println(" 1 2 3 4 5 6 7 8 9 10");
for(double i=1;i<=10;i++){
System.out.print(df.format(i)+" ");
if (i<10) System.out.print(" ");
else System.out.print("");
for(double j=1;j<=10;j++){
double div=(j/i);
System.out.print(df.format(div));
if (div < 10) System.out.print(" ");
}
System.out.println();
this prints
1 2 3 4 5 6 7 8 9 10
1 1 2 3 4 5 6 7 8 9 10
2 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
3 0.33 0.67 1 1.33 1.67 2 2.33 2.67 3 3.33
4 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5
5 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
6 0.17 0.33 0.5 0.67 0.83 1 1.17 1.33 1.5 1.67
7 0.14 0.29 0.43 0.57 0.71 0.86 1 1.14 1.29 1.43
8 0.12 0.25 0.38 0.5 0.62 0.75 0.88 1 1.12 1.25
9 0.11 0.22 0.33 0.44 0.56 0.67 0.78 0.89 1 1.11
10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
i want to print everything as x.xx or neatly in columns
1 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0
2 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00
3 0.33 0.67 1.00 1.33 1.67 2.00 2.33 2.67 3.00 3.33
etc
Many ways, but one is to use String.format("%.2f", myDouble)
Another way is to use a DecimalFormat such as DecimalFormat format = new DecimalFormat("#0.00")
and then use it like format.format(myDouble)
To format a table, use String.format(...)
or one of its variants like printf.
e.g.
public class Foo2 {
private static final int COLS = 10;
private static final int ROWS = 10;
public static void main(String[] args) {
System.out.printf("%2s", "");
for (int i = 0; i < COLS; i++) {
System.out.printf("%8d", (i + 1));
}
System.out.println();
for (int i = 0; i < ROWS; i++) {
int row = i + 1;
System.out.printf("%2d", row);
for (int j = 0; j < ROWS; j++) {
double myDouble = (double) row / (j + 1);
System.out.printf("%8.2f", myDouble);
}
System.out.println();
}
}
}
which prints out
1 2 3 4 5 6 7 8 9 10
1 1.00 0.50 0.33 0.25 0.20 0.17 0.14 0.13 0.11 0.10
2 2.00 1.00 0.67 0.50 0.40 0.33 0.29 0.25 0.22 0.20
3 3.00 1.50 1.00 0.75 0.60 0.50 0.43 0.38 0.33 0.30
4 4.00 2.00 1.33 1.00 0.80 0.67 0.57 0.50 0.44 0.40
5 5.00 2.50 1.67 1.25 1.00 0.83 0.71 0.63 0.56 0.50
6 6.00 3.00 2.00 1.50 1.20 1.00 0.86 0.75 0.67 0.60
7 7.00 3.50 2.33 1.75 1.40 1.17 1.00 0.88 0.78 0.70
8 8.00 4.00 2.67 2.00 1.60 1.33 1.14 1.00 0.89 0.80
9 9.00 4.50 3.00 2.25 1.80 1.50 1.29 1.13 1.00 0.90
10 10.00 5.00 3.33 2.50 2.00 1.67 1.43 1.25 1.11 1.00
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