Method Recursion in Java Method
Recursion
Recursion is an algorithm that is widely used in programming languages.
The form in which a method calls itself is called method recursion.
Forms of recursion
Direct recursion: The method calls itself.
Indirect recursion: methods call other methods, and other methods call back the method itself.
Precautions for method recursion
If the recursion is not terminated properly, a recursive infinite loop will occur, resulting in stack memory overflow.
Three elements of a recursive algorithm
Recursive formula
Recursive end point
The direction of recursion must go to the end point
public class Recursion01 {
public static void main(String[] args) {
T t = new T();
t.test(4);
}
}
class T {
public void test(int n) {
if(n > 2) {
test(n-1);
}
System.out.println(n);
}
}
The running results are as follows:
2
3
4
public class Recursion01 {
public static void main(String[] args) {
T t = new T();
t.test(4);
}
}
class T {
public void test(int n) {
if(n > 2) {
test(n-1);
}else {
System.out.println(n);
}
}
}
Note the difference between Example 1 and Example 2. Example 1 is to execute the test method, and the current n will be printed. Example 2 is to make a judgment that it is less than or equal to 2 and print the current n.
recursive sum
public class diguiqiuhe {
public static void main( String[] args ) {
int num=5;
int sum=getSum(num);
System.out.println(sum);
}
private static int getSum( int num ) {
if (num==1){
return 1;
}
return num+getSum(num-1);
}
}
