import java.util.Scanner;
public class Maintest {
static Scanner kb = new Scanner(System.in);
public static void main (String args[]) {
System.out.println("This is how you should format your equation => 3.0 x + 5.5 y = 9.0");
System.out.println("Type your first equation:");
String first = kb.nextLine();
//first equation
Scanner one = new Scanner(first);
//scanner for first
double[] arr = new double[6];
//arr containing numbers
String[] vars = new String[2];
//arr containing variable names
System.out.println("Type your second equation:");
String second = kb.nextLine();
//second equations
Scanner two = new Scanner(second);
//scanner for second
one.useDelimiter("[^\\p{Alnum},\\.-]");
two.useDelimiter("[^\\p{Alnum},\\.-]");
//anything other than alphanumberic characters,
//comma, dot or negative sign is skipped
for (int i = 1; i <= 3; i++) {
if (one.hasNextDouble())
arr[i-1] = one.nextDouble();
else if (one.hasNext())
vars[i-1] = one.next();
else if (two.hasNextDouble())
arr[i+2] = one.nextDouble();
else if (arr[i-1] == 0.0)
arr[i-1] = 1.0;
//putting values into array
}
System.out.println(arr[3]);
System.out.println(vars[2]);
}
}
我想知道我的代码有什么问题。它应该解决线性方程组,但是现在,我正在研究人们输入的方程中的值。我期望它打印出我告诉它的数组的特定索引的值打印(即arr [3]和vars [2]),但它说java.lang.ArrayIndexOutOfBoundsException:2。请你帮忙,可能告诉我我的错误?哦,我想知道一种更有效的方法来完成相同数量的代码,甚至可以让用户只输入3x + 4.5y = 15而不需要所有不必要的空格或.0。谢谢你的帮助!
答案 0 :(得分:1)
如您所见,vars
是一个第二个数组:
String[] vars = new String[2];
由于Java索引从零开始,这意味着该数组具有两个字符串的“空间”:vars[0]
和vars[1]
。除此之外的任何事情都是越界的,这就是你得到错误的原因:
System.out.println(vars[2]); //vars[2] would be the third String, but vars's length is only two!
您还应该确保在打印语句之前的循环中没有尝试访问vars[2]
。