How to print a table of information in Java
I'm trying to print a table in Java and I was wondering what is the best way to do this?
I've tried printing new lines and using \t to make contents line up but it doesn't work. Is there a method which does this or a better way?
You can use System.out.format(...)
Example:
final Object[][] table = new String[4][];
table[0] = new String[] { "foo", "bar", "baz" };
table[1] = new String[] { "bar2", "foo2", "baz2" };
table[2] = new String[] { "baz3", "bar3", "foo3" };
table[3] = new String[] { "foo4", "bar4", "baz4" };
for (final Object[] row : table) {
System.out.format("%15s%15s%15s%n", row);
}
Result:
foo bar baz
bar2 foo2 baz2
baz3 bar3 foo3
foo4 bar4 baz4
Or use the following code for left-aligned output:
System.out.format("%-15s%-15s%-15s%n", row);
General function to table-format a list of arrays:
public static String formatAsTable(List<List<String>> rows)
{
int[] maxLengths = new int[rows.get(0).size()];
for (List<String> row : rows)
{
for (int i = 0; i < row.size(); i++)
{
maxLengths[i] = Math.max(maxLengths[i], row.get(i).length());
}
}
StringBuilder formatBuilder = new StringBuilder();
for (int maxLength : maxLengths)
{
formatBuilder.append("%-").append(maxLength + 2).append("s");
}
String format = formatBuilder.toString();
StringBuilder result = new StringBuilder();
for (List<String> row : rows)
{
result.append(String.format(format, row.toArray(new String[0]))).append("\n");
}
return result.toString();
}
Usage:
List<List<String>> rows = new ArrayList<>();
List<String> headers = Arrays.asList("Database", "Maintainer", "First public release date", "Latest stable version", "Latest release date");
rows.add(headers);
rows.add(Arrays.asList("4D (4th Dimension)", "4D S.A.S.", "1984", "v16.0", "2017-01-10"));
rows.add(Arrays.asList("ADABAS", "Software AG", "1970", "8.1", "2013-06"));
rows.add(Arrays.asList("Adaptive Server Enterprise", "SAP AG", "1987", "16.0", "2015"));
rows.add(Arrays.asList("Apache Derby", "Apache", "2004", "10.14.1.0", "2017-10-22"));
System.out.println(formatAsTable(rows));
The result:
Database Maintainer First public release date Latest stable version Latest release date
4D (4th Dimension) 4D S.A.S. 1984 v16.0 2017-01-10
ADABAS Software AG 1970 8.1 2013-06
Adaptive Server Enterprise SAP AG 1987 16.0 2015
Apache Derby Apache 2004 10.14.1.0 2017-10-22
This is one way to do it:
public class StoreItem {
private String itemName;
private double price;
private int quantity;
public StoreItem(String itemName, double price, int quantity) {
this.setItemName(itemName);
this.setPrice(price);
this.setQuantity(quantity);
}
public String getItemName() {
return itemName;
}
public void setItemName(String itemName) {
this.itemName = itemName;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public int getQuantity() {
return quantity;
}
public void setQuantity(int quantity) {
this.quantity = quantity;
}
public static void printInvoiceHeader() {
System.out.println(String.format("%30s %25s %10s %25s %10s", "Item", "|", "Price($)", "|", "Qty"));
System.out.println(String.format("%s", "----------------------------------------------------------------------------------------------------------------"));
}
public void printInvoice() {
System.out.println(String.format("%30s %25s %10.2f %25s %10s", this.getItemName(), "|", this.getPrice(), "|", this.getQuantity()));
}
public static List<StoreItem> buildInvoice() {
List<StoreItem> itemList = new ArrayList<>();
itemList.add(new StoreItem("Nestle Decaff Coffee", 759.99, 2));
itemList.add(new StoreItem("Brown's Soft Tissue Paper", 15.80, 2));
itemList.add(new StoreItem("LG 500Mb External Drive", 700.00, 2));
return itemList;
}
public static void main (String[] args) {
StoreItem.printInvoiceHeader();
StoreItem.buildInvoice().forEach(StoreItem::printInvoice);
}
}
Output:
Write a function which pads a string to your desired column-length with spaces. This can be a static helper, and you can create a class StrUtils or similar to hold it.
(There may also be Apache or other libraries with String helpers/utils to do this for you.)
Long-term, if you're outputting tabular data you could consider exporting CSV (for Excel etc) or XML. But these are for typical long-term business requirements, not just a quick to-screen output.