How to format java output like a table

Question

I have a data structure that i would like to print on the output like a table.

i've usedSystem.Out printf method but the result is not good.

System.out.printf("%4s  %-7s   %-4s   %-7s%n", "node", "node Ip", "Type", "subType");
System.out.printf("%2d  %-7s   %-12s   %-21s%n", node.getNodeKey(),
              node.getNodeIpAddress(), 
              node.getNodeType(), 
              node.getNodeSubType());

and the result is:

node  node Ip   Type   subType
 2  10.1.1.2   NODETYPE_WDM   NODESUBTYPE_RROADM_2 
 0            NODETYPE_NONE   NODESUBTYPE_NONE

is there any smart way to do this well?

Thanks a lot.

CPerkins · Accepted Answer · 2013-11-12 18:03:41Z

1

That depends on what you mean by "smart", I think.

But to continue with the way you're doing it, try two things:

1) Header row field widths must be the same size as data row widths; and
2) You'll want them to be big enough.

This shows you what I mean:

  public void printLineImproved (int node, String nodeIp, String nodeType, String nodeSubtype) {
    System.out.printf("%4s  %-12s   %-12s   %-21s%n", "node", "node Ip", "Type", "subType");
    System.out.printf("%4d  %-12s   %-12s   %-21s%n", node, nodeIp, nodeType, nodeSubtype);
  }

The output from that is:

node  node Ip        Type           subType              
   2  10.1.1.2       NODETYPE_WDM   NODESUBTYHPE_RROADM_2

answered Nov 12, 2013 at 18:03

CPerkins

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2 Comments

M4tt3 Over a year ago

when i've said smart i meant solution more generic and automatic than mine. For example don't format the size of all the coloumn. Because i've a lot of data and some of the possible value are enumerated.

CPerkins Over a year ago

@M4tt3 Yes, there are such solutions. Sage's answer addresses that. Mine just fixed your errors with the widths.

Sage · Accepted Answer · 2013-11-12 18:52:38Z

1

If the data is already read inside a memory and we can work with them offline: means that data is not essentially appearing one by one, or if so it is possible to store them inside a table: a 2D array like data structure or collection to work with before-hand:

we can try computing maximum width of each column
Then use the maximum width as formatting flag: "%"+maxWidth[col]+"s";

I am providing a short working example for you:

String data[][] = { {"Id", "Vehicle", "Disance" },
                    {"1", "ByCycle", "2 km"}, 
                    {"2", "Car", "10 km"}, 
                    {"3", "Van", "6.5 km"} 
                  };

        int col = data[0].length;
        int row = data.length;

        int maxWidth[] = new int[col];

        for(String[] rowD : data)
         for(int i=0; i< col; i++)
         {
             if(maxWidth[i] < rowD[i].length())
                 maxWidth[i] = rowD[i].length();
         }

        String format = "";

        for(int x:maxWidth)
            format += "%-"+(x+2)+"s ";

        format +="%n";

        for(String[] rowD : data)
        {
            System.out.printf(format, rowD);
        }

The sample output will be:

Id   Vehicle   Disance   
1    ByCycle   2 km      
2    Car       10 km     
3    Van       6.5 km

answered Nov 12, 2013 at 18:52

Sage

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1 Comment

Edric Over a year ago

Your sample code seems to have some issues - 1. The row integer variable seems to be unused. 2. There's some inconsistencies in the spacing in the for loop's conditions. 3. There's some misspellings in the data - "ByCycle" should be "Bicycle" and "Disance" should be "Distance"

Akira · Accepted Answer · 2013-11-12 17:47:24Z

0

Most straight forward way is to use tab characters "\t". But this is not guaranteed to work if the length of any printed string is larger than tab. Also, the width of tab depends on many factors.

The best way to accomplish what you need is by checking the maximum width of each column and add space characters as needed to make the layout beautiful.

answered Nov 12, 2013 at 17:47

Akira

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