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:

<br />
returntype methodname(){<br />
//code to be executed<br />
methodname();//calling same method<br />
}<br />

Java Recursion Example 1: Infinite times

<br />
public class RecursionExample1 {<br />
static void p(){<br />
System.out.println(“hello”);<br />
p();<br />
}</p>
<p>public static void main(String[] args) {<br />p();<br />}<br />}<br />

Output:

hello
hello
...
java.lang.StackOverflowError

Java Recursion Example 2: Finite times

<br />
public class RecursionExample2 {<br />
static int count=0;<br />
static void p(){<br />
count++;<br />
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 Number

<br />
public class RecursionExample3 {<br />
	static int factorial(int n){<br />
		  if (n == 1)<br />
		    return 1;<br />
		  else<br />
		    return(n * factorial(n-1));<br />
	}    </p>
<p>public static void main(String[] args) {<br />System.out.println(“Factorial of 5 is: “+factorial(5));<br />}<br />}<br />

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 Series

<br />
public class RecursionExample4 {<br />
	static int n1=0,n2=1,n3=0;<br />
	 static void printFibo(int count){<br />
	    if(count>0){<br />
	         n3 = n1 + n2;<br />
	         n1 = n2;<br />
	         n2 = n3;<br />
	         System.out.print(” “+n3);<br />
	         printFibo(count-1);<br />
	     }<br />
	 }      </p>
<p>public static void main(String[] args) {<br />	int count=15;<br />	  System.out.print(n1+” “+n2);//printing 0 and 1<br />	  printFibo(count-2);//n-2 because 2 numbers are already printed<br />}<br />}<br />

Output:

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377

原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/tech/pnotes/263812.html

Recursion in Java

Recursion in Java

Java Recursion Example 1: Infinite times

Java Recursion Example 2: Finite times

Java Recursion Example 3: Factorial Number

Java Recursion Example 4: Fibonacci Series

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