find duplicate characters in a String?

 find duplicate characters in a String? (solution)
You need to write a program to print all duplicate character and their count in Java. For example if given String is "Programming" then your program should print
g : 2
r : 2
m : 2

Author: singhvirendra18gmailcom

Challenge06.java

@@ -0,0 +1,39 @@
+package challenge06;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import org.junit.Test;
+
+/**
+ * The Class Challenge06.
+ * 
+ *   find duplicate characters in a String.
+ *   You need to write a program to print all duplicate character 
+ *   and their count in Java. For example if given String
+ *   is "Programming" then your program should print
+ *   g : 2
+ *   r : 2
+ *   m : 2
+ */
+public class Challenge06 {
+
+	public static void printduplcatesWithCount(String input) {
+		Map<Character, Integer> counter=new LinkedHashMap<Character, Integer>();
+		for(int i=0;i<input.length()-1;i++) {
+			Integer oldvalue=counter.put(input.charAt(i), 1);
+			if(oldvalue!=null) {
+				counter.put(input.charAt(i), oldvalue+1);
+			}
+		}
+		
+		counter.forEach((k,v)-> System.out.println(k +" :" + v));
+		
+			
+	}
+	
+	@Test
+	public void test() {
+		Challenge06.printduplcatesWithCount("{Programming");
+	}
+}