what does string.format do in java code example

Example: java string format

public class FormatExample{  
public static void main(String args[]){  
String name="sonoo";  
String sf1=String.format("name is %s",name);  
String sf2=String.format("value is %f",32.33434);  
String sf3=String.format("value is %32.12f",32.33434);//returns 12 char fractional part filling with 0  
  
System.out.println(sf1);  
System.out.println(sf2);  
System.out.println(sf3);  
}}