索引 12 超出了长度 12 的范围。我该如何解决这个问题？

Question

Everytime I run the code I get an Index 12 out of bounds for length 12. I'm not sure what is the problem. Here is the code:

enter code here: int getDayNumber(int day,int month,int year) {
    if(this.leapYear(year)) {
        int months[] = {31,29,31,30,31,30,31,31,30,31,30,31};
        int cnt = 0 ;
        for(int i=0;i<month-1;i++) {
            cnt += months[i];
            System.out.println(cnt + "   " + i);
        }
        return cnt + day ; // count = cnt

   

Answer 1

The (month - 1) that you've used inside the loop points to the month passed in the parameter in the function getDayNumber. Consider using.length function to calculate the length of the array. Try using for loop something like:

for(int i = 0 ; i < months.length ; i++)

Your concept of how Array works is pretty clear. Just use months.length and you're good to go. Tell me how this works out for you!

Answer 2

    package projectlearn1;

public class ArrayQueue {
    private int[] mArray;
    private int mCount;

    public ArrayQueue(int sz) {
        mArray=new int[sz];
        mCount=0;
    }

    public void add(int val){
        mArray[mCount++]=val;
    }

    public int front(){
        return mArray[0];
    }

    public int pop(){
        int ret=mArray[0];
        mCount--;
        for (int i = 0; i < mCount; i++) {
            mArray[i-1]=mArray[i];
        }
        return ret;
    }
    public int size(){
        return mCount;
    }

    public boolean isEmpty(){
        return size()==0;
    }

    public static void main(String[] args) {
        int tmp=0;
        ArrayQueue astack=new ArrayQueue(12);
        astack.add(10);
        astack.add(20);
        astack.add(30);

        tmp=astack.pop();
        System.out.printf("tmp=%d\n",tmp);

        tmp=astack.front();
        System.out.printf("tmp=%d\n",tmp);

        astack.add(40);

        System.out.printf("isEmpty()=%b\n",astack.isEmpty());
        System.out.printf("size()=%d\n",astack.size());
        while (!astack.isEmpty()){
            System.out.printf("size()=%d\n",astack.pop());
        }
    }
}

Answer 3

import java.util.*; public class BinaryTreessssB {

static class Node {
    int data;
    Node left;
    Node right;

    Node(int data) {
        this.data = data;
        this.left = null;
        this.right = null;
    }

}
static class BinaryTree{
    static int idx = -1;
    public static Node buildTree(int nodes[]){
        idx++;
        if (nodes[idx] == -1){
            return null;
        }
        Node newNode = new Node(nodes[idx]);
        newNode.left = buildTree(nodes);
        newNode.right = buildTree(nodes);


        return newNode;
    }

    public static void preorder(Node root){
        if (root == null){

        }
        System.out.println(root.data+" ");
        preorder(root.left);
        preorder(root.right);
    }

}
public static void main(String[] args) {
    int nodes[] = {1, 2, 4, -1, 5, -1, -1, 3, -1, 6, -1, -1};
    BinaryTree tree = new BinaryTree();
    Node root = tree.buildTree(nodes);
    tree.preorder(root);
}

} enter image description here