如何确定java.lang.ArrayIndexOutOfBoundsException的原因?
这是以下内容的延续: 我一直在 尝试运行代码时出现如何确定java.lang.ArrayIndexOutOfBoundsException的原因?,java,debugging,Java,Debugging,这是以下内容的延续: 我一直在 尝试运行代码时出现java.lang.ArrayIndexOutOfBoundsException错误。我得到了第63行和第40行的错误,它们是 63: int fib = dictionary[num]; // dictionary is a class level array. 40: answer = fibonacci(num); // Answer is an int calling the fibonacci function and passing
java.lang.ArrayIndexOutOfBoundsException
错误。我得到了第63行和第40行的错误,它们是
63: int fib = dictionary[num]; // dictionary is a class level array.
40: answer = fibonacci(num); // Answer is an int calling the fibonacci function and passing "num" to it.
以下是完整的代码:
import javax.swing.JOptionPane;
public class question2
{
//class variable
static int count = 0;
static int [] dictionary;
//main method
public static void main(String[] args)
{
//user input
int num = Integer.parseInt(JOptionPane.showInputDialog("Enter num:")), answer;
//Catches negative numbers, exits
if (num < 0)
{
JOptionPane.showMessageDialog(null,"ERROR: fibonacci sequence not defined for negative numbers.");
System.exit(1);
}
//info dialog
JOptionPane.showMessageDialog(null,"About to calculate fibonacci("+num+")");
//giving the array "num" elements
dictionary = new int [num];
//fill array with 0
for (int i=0; i<dictionary.length;i++)
dictionary[i]=0;
//adds value of 1 for fib(1)
if (dictionary.length>=2)
dictionary[1]= 1;
//method call
answer = fibonacci(num);
//output
JOptionPane.showMessageDialog(null,"Fibonacci("+num+") is "+answer+" (took "+count+" calls)");
}
static int fibonacci(int num)
{
count++;
// Base cases: f(0) is 0, f(1) is 1
if (num==0)
return 0;
if (num==1)
return 1;
// Other cases: f(num) = f(num-1) + f(num-2)/
else
{
//check array for value
int fib = dictionary[num];
//add new value to array
if (fib==0)
{
fib = fibonacci(num-1) + fibonacci(num-2);
dictionary[num] = fib;
}
return fib;
}
}
} //class terminator
import javax.swing.JOptionPane;
公开课问题2
{
//类变量
静态整数计数=0;
静态int[]字典;
//主要方法
公共静态void main(字符串[]args)
{
//用户输入
int num=Integer.parseInt(JOptionPane.showInputDialog(“输入num:”),回答;
//捕捉负数,退出
if(num<0)
{
showMessageDialog(null,“错误:未为负数定义斐波那契序列”);
系统出口(1);
}
//信息对话框
showMessageDialog(null,“即将计算斐波那契(“+num+”));
//给数组指定“num”元素
dictionary=newint[num];
//用0填充数组
对于(int i=0;i=2)
字典[1]=1;
//方法调用
答案=斐波那契(num);
//输出
showMessageDialog(null,“Fibonacci(+num+”)是“+answer+”(take“+count+”calls)”);
}
静态整数斐波那契(整数)
{
计数++;
//基本情况:f(0)为0,f(1)为1
如果(num==0)
返回0;
如果(num==1)
返回1;
//其他情况:f(num)=f(num-1)+f(num-2)/
其他的
{
//检查数组的值
int fib=字典[num];
//向数组添加新值
如果(fib==0)
{
fib=fibonacci(num-1)+fibonacci(num-2);
字典[num]=fib;
}
返回fib;
}
}
}//类终止符
数组的大小为num
(int fib=dictionary[num];
),因此您可以访问的最大索引是num-1
。您尝试访问索引num
(dictionary[num]=fib;
),这超出了范围。数组的大小为num
(int fib=dictionary[num];
),因此您可以访问的最大索引是num-1
。你试图访问索引num
(dictionary[num]=fib;
),这是不允许的。如果你完全被这类事情困住了,用调试器去做就是了。如果你完全被这类事情困住了,用调试器去做就是了。快速修复:在输入的数字上加1,并调用fibonacci(num-1)
QuickFix:在输入的号码中添加1,然后调用fibonacci(num-1)