Can we execute without main () method Program in java

// * execute without main method Program *//

class Maind
{
static
{
System.out.println("Hello execute without main method.");
System.exit(0);
}
}

Compile :     javac Maind.java
       Run :    java Maind
Output :-
               Hello execute without main method.

______________________________________________

// *....... execute without main method Program........... /

class Maind
{
static
{
System.out.println("Hello execute without main method.");
}
}

Compile : javac Maind.java
Run: java Maind

Output :-
               Hello execute without main method.
               Exception in thread "main" java.lang.NoSuchMethodError: main

how to Remove Duplicate Charatcers From String (i.e. AAA BBB---AB)

import java.util.*;

//class RemoveDuplicateCharatcersFromString = Main9
class Main9
{
public static String removeDuplicates(String s) {
StringBuilder build = new StringBuilder();
for (int i = 0; i < s.length(); i++) {
String st = s.substring(i, i + 1);
if (build.indexOf(st) == -1) {
build.append(st);
}
}
return build.toString();
}
public static void main(String[] args)
{
String str="AAA BBB ";
String newString=removeDuplicates(str);
System.out.println(newString);
}
}
out put:-
                 A B

How to use method for calculating Fibonacci series?

public class MainClass {
   public static long fibonacci(long number) {
      if ((number == 0) || (number == 1))
         return number;
      else
         return fibonacci(number - 1) + fibonacci(number - 2);
   }
   public static void main(String[] args) {
      for (int counter = 0; counter <= 10; counter++){
         System.out.printf("Fibonacci of %d is: %d\n",
         counter, fibonacci(counter));
      }
   }
}

output:

 
Fibonacci of 0 is: 0
Fibonacci of 1 is: 1
Fibonacci of 2 is: 1
Fibonacci of 3 is: 2
Fibonacci of 4 is: 3
Fibonacci of 5 is: 5
Fibonacci of 6 is: 8
Fibonacci of 7 is: 13
Fibonacci of 8 is: 21
Fibonacci of 9 is: 34
Fibonacci of 10 is: 55

How to find the minimum and the maximum element in an array

import java.util.Arrays;
import java.util.Collections;

public class Main3 {
   public static void main(String[] args) {
      Integer[] numbers = { 8, 2, 7, 15, 4, 9, 5,99};
      int min = (int) Collections.min(Arrays.asList(numbers));
      int max = (int) Collections.max(Arrays.asList(numbers));
      System.out.println("Min number: " + min);
      System.out.println("Max number: " + max);
   }
}

// *.....How to reverse array........*//

import java.util.ArrayList;
import java.util.Collections;

public class Main {
   public static void main(String[] args) {
      ArrayList arrayList = new ArrayList();
      arrayList.add("A");
      arrayList.add("B");
      arrayList.add("C");
      arrayList.add("D");
      arrayList.add("E");
      System.out.println("Before Reverse Order: " + arrayList);
      Collections.reverse(arrayList);
      System.out.println("After Reverse Order: " + arrayList);
   }
}

o/p:

Before Reverse :- [A, B, C, D, E]
After  Reverse :- [E, D, C, B, A]