Why is this Java formatted output not right-justified?

问题

I'm a beginner, and I'm experimenting with formatted output.
I'm trying to produce a table of decimals:

for (int i = 0; i < 8; i++) {
  for (int j = 0; j < 8; j++) {
    row = (double) 5*i;
    column = (double) j + 1;
    System.out.format("% 6.3f", row/column);
    System.out.print("\t");
  }
  System.out.format("%n");
}

This produces:

 0.000   0.000    0.000   0.000   0.000   0.000   0.000   0.000 
 5.000   2.500    1.667   1.250   1.000   0.833   0.714   0.625 
 10.000 5.000    3.333   2.500   2.000   1.667   1.429   1.250  
 15.000 7.500    5.000   3.750   3.000   2.500   2.143   1.875  
 20.000 10.000   6.667   5.000   4.000   3.333   2.857   2.500  
 25.000 12.500   8.333   6.250   5.000   4.167   3.571   3.125  
 30.000 15.000   10.000  7.500   6.000   5.000   4.286   3.750  
 35.000 17.500   11.667  8.750   7.000   5.833   5.000   4.375

The API says that if the '-' flag is not thrown, then the output will be right-justified, which is what I want. I have put ' ' after % to indicate that I want the output padded with spaces when necessary. What am I missing?

(I haven't used the homework tag, because I am not enrolled in any course.)

回答1:

You have added a space incorrectly into the formatting String:

System.out.format("% 6.3f", row/column);

Should be:

System.out.format("%6.3f", row/column);

And you get:

 0.000         0.000         0.000         0.000         0.000         0.000         0.000         0.000        
 5.000         2.500         1.667         1.250         1.000         0.833         0.714         0.625        
10.000         5.000         3.333         2.500         2.000         1.667         1.429         1.250        
15.000         7.500         5.000         3.750         3.000         2.500         2.143         1.875        
20.000        10.000         6.667         5.000         4.000         3.333         2.857         2.500        
25.000        12.500         8.333         6.250         5.000         4.167         3.571         3.125        
30.000        15.000        10.000         7.500         6.000         5.000         4.286         3.750        
35.000        17.500        11.667         8.750         7.000         5.833         5.000         4.375

来源：https://stackoverflow.com/questions/828771/why-is-this-java-formatted-output-not-right-justified

标签

java

formatting