format statement in a string resource file

You do not need to use formatted="false" in your XML. You just need to use fully qualified string format markers - %[POSITION]$[TYPE] (where [POSITION] is the attribute position and [TYPE] is the variable type), rather than the short versions, for example %s or %d.

Quote from Android Docs: String Formatting and Styling:

<string name="welcome_messages">Hello, %1$s! You have %2$d new messages.</string>

In this example, the format string has two arguments: %1$s is a string and %2$d is a decimal integer. You can format the string with arguments from your application like this:

Resources res = getResources();
String text = res.getString(R.string.welcome_messages, username, mailCount);

You should add formatted="false" to your string resource

Here is an example

In your strings.xml :

<string name="all" formatted="false">Amount: %.2f%n  for %d days</string>

In your code:

yourTextView.setText(String.format(getString(R.string.all), 3.12, 2));

Inside file strings.xml define a String resource like this:

<string name="string_to_format">Amount: %1$f  for %2$d days%3$s</string>

Inside your code (assume it inherits from Context) simply do the following:

 String formattedString = getString(R.string.string_to_format, floatVar, decimalVar, stringVar);

(In comparison to the answer from LocalPCGuy or Giovanny Farto M. the String.format method is not needed.)