NumberFormatException.for InputString ： "("

Question

在运行我的代码时，我将获得numberFormateXception：

Exception in thread "main" java.lang.NumberFormatException: For input string: "("
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:569)
    at java.lang.Integer.parseInt(Integer.java:615)
    at collection.MyExpressionTrees.evaluateHelper(MyExpressionTrees.java:58)
    at collection.MyExpressionTrees.evaluateHelper(MyExpressionTrees.java:78)
    at collection.MyExpressionTrees.evaluate(MyExpressionTrees.java:50)

public class MyExpressionTrees extends MyBinaryTree {
public MyExpressionTrees() {
    root = null;
}
public MyExpressionTrees(MyBinaryTreeNode rt) {
    root = rt;
}
public int evaluate() {
    if (root == null) {
        return -1000000;
    }
    return evaluateHelper(root);
}
private int evaluateHelper(MyBinaryTreeNode rt) {
    if (rt.left == null) {
        return Integer.parseInt(rt.data.toString());
    }
    switch (rt.data.toString()) {
        case "+":
            return evaluateHelper(rt.left) + evaluateHelper(rt.right);
        case "-":
            return evaluateHelper(rt.left) - evaluateHelper(rt.right);
        case "/":
            return evaluateHelper(rt.left) / evaluateHelper(rt.right);
        case "*":
            return evaluateHelper(rt.left) * evaluateHelper(rt.right);
        case "%":
            return evaluateHelper(rt.left) % evaluateHelper(rt.right);
        default:
            return -1000000;
    }
}
}

Answer 1

numberFormateXception：

投掷以指示应用程序 试图将字符串转换为数字类型之一，但是 字符串没有适当的格式。

public static int parseint(字符串S(：

将字符串参数解析为签名的十进制整数。那些角色 字符串中必须全部是十进制数字，除了第一个 字符可能是ASCII负符号' - '(' u002d'(，以指示一个 负值或ASCII加上符号' '(' u002b'(表示一个 正值。结果整数值返回，就像 论点和radix 10被作为论据 parseint(java.lang.string，int(方法。

"("不是数字。

是的，famalam fammy！

Answer 2

公共类Project_t {

private static final String fpath = "../COSC241_P4_Input.txt";
private static MyExpressionTree exTree = new MyExpressionTree();
private static List<String> infList;
private static final MyDeque d = new MyDeque();
private static final MyStack st = new MyStack();
private static int result;
/**
 *
 * Test method for the project. Handles file input and output, as well as *
 * running tests on each expression in the input file. *
 */
public static void test() {
    result = 0;
    File out = new File("../COSC241_P4_Output_tdreed0.txt");
    try {
        //Stores each line of the file in a list.
        infList = FP.readFile(fpath).stream().filter((s) -> !s.isEmpty()).collect(Collectors.toList());
        //If the output file does not currently exist, create it.
        if (!out.exists()) {
            out.createNewFile();
        }
        try (PrintWriter writer = new PrintWriter(out)) {
            for (String s : infList) {
                String root = s.trim().replaceAll(" ", "").replaceAll("\[", "(").replaceAll("\]", ")");
                writer.println("Original Infix:t" + root);
                if (!ExpressionRegulators.allPMatched(root) || !ExpressionRegulators.allValid(root) || !ExpressionRegulators.isValidOrder(root)) {
                    writer.println("Invalid Expression");
                    writer.println();
                } else {
                    buildExpressionTree(root);
                    //Performs traversals on the tree
                    exTree.preorderTraversal();
                    writer.println("Preorder: " + exTree.preorderStr);
                    exTree.inorderTraversal();
                    writer.println("Inorder: " + exTree.inorderStr);
                    exTree.postorderTraversal();
                    writer.println("Postorder: " + exTree.postorderStr);
                    result = exTree.evaluate();
                    writer.println("Result: " + result);
                    writer.println();
                    exTree.clear();
                }
            }
        }
    } catch (IOException e) {
        System.out.println(e.toString());
        System.exit(0);
    }
}