/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String s = "2016/10/10 10:10:10"; 
		String rx = "(\\d{4})/(\\d{2})/(\\d{2} \\d{2}:\\d{2}:\\d{2})";
		System.out.println(s.replaceAll(rx, "$1-$2-$3")); 
	}
}

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