我有一段代码,但无法确定为什么它会报错 Exception in thread "main" java.lang.StackOverflowError。
以下是问题:
Given a positive integer n, prints out the sum of the lengths of the Syracuse
sequence starting in the range of 1 to n inclusive. So, for example, the call:
lengths(3)
will return the the combined length of the sequences:
1
2 1
3 10 5 16 8 4 2 1
which is the value: 11. lengths must throw an IllegalArgumentException if
its input value is less than one.
我的代码:
import java.util.HashMap;
public class Test {
HashMap<Integer,Integer> syraSumHashTable = new HashMap<Integer,Integer>();
public Test(){
}
public int lengths(int n)throws IllegalArgumentException{
int sum =0;
if(n < 1){
throw new IllegalArgumentException("Error!! Invalid Input!");
}
else{
for(int i =1; i<=n;i++){
if(syraSumHashTable.get(i)==null)
{
syraSumHashTable.put(i, printSyra(i,1));
sum += (Integer)syraSumHashTable.get(i);
}
else{
sum += (Integer)syraSumHashTable.get(i);
}
}
return sum;
}
}
private int printSyra(int num, int count){
int n = num;
if(n == 1){
return count;
}
else{
if(n%2==0){
return printSyra(n/2, ++count);
}
else{
return printSyra((n*3)+1, ++count) ;
}
}
}
}
驱动程序代码:
public static void main(String[] args) {
// TODO Auto-generated method stub
Test s1 = new Test();
System.out.println(s1.lengths(90090249));
//System.out.println(s1.lengths(5));
}
我知道问题出在递归上。如果输入值很小,例如:5,则不会出现错误。但是当数字很大时,例如90090249,我会收到“Exception in thread "main" java.lang.StackOverflowError”的错误。感谢大家的帮助。:)
我差点忘了错误信息:
Exception in thread "main" java.lang.StackOverflowError
at Test.printSyra(Test.java:60)
at Test.printSyra(Test.java:65)
at Test.printSyra(Test.java:60)
at Test.printSyra(Test.java:65)
at Test.printSyra(Test.java:60)
at Test.printSyra(Test.java:60)
at Test.printSyra(Test.java:60)
at Test.printSyra(Test.java:60)
printSyra(i,1)
方法在哪里? - Rohit JainprintSyra
调用了printSyra
。 - Pshemo