Recursion in Java
Recursion in java is a process in which a method calls itself continuously. A method in java that calls itself is called recursive method.
It makes the code compact but complex to understand.
Syntax:
returntype methodname(){ //code to be executed methodname();//calling same method } Java Recursion Example 1: Infinite timespublic class RecursionExample1 { static void p(){ System.out.println("hello"); p(); }
public static void main(String[] args) { p(); } }
Output:
hello hello ... java.lang.StackOverflowError Java Recursion Example 2: Finite timespublic class RecursionExample2 { static int count=0; static void p(){ count++; if(count<=5){ System.out.println("hello "+count); p(); } } public static void main(String[] args) { p(); } }
Output:
hello 1 hello 2 hello 3 hello 4 hello 5 Java Recursion Example 3: Factorial Numberpublic class RecursionExample3 { static int factorial(int n){ if (n == 1) return 1; else return(n * factorial(n-1)); }
public static void main(String[] args) { System.out.println("Factorial of 5 is: "+factorial(5)); } }
Output:
Factorial of 5 is: 120
Working of above program:
factorial(5) factorial(4) factorial(3) factorial(2) factorial(1) return 1 return 2*1 = 2 return 3*2 = 6 return 4*6 = 24 return 5*24 = 120 Java Recursion Example 4: Fibonacci Seriespublic class RecursionExample4 { static int n1=0,n2=1,n3=0; static void printFibo(int count){ if(count>0){ n3 = n1 + n2; n1 = n2; n2 = n3; System.out.print(" "+n3); printFibo(count-1); } }
public static void main(String[] args) { int count=15; System.out.print(n1+" "+n2);//printing 0 and 1 printFibo(count-2);//n-2 because 2 numbers are already printed } }
Output:
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377
