int[] a = new int[5];
其默认初始化的值为{0，0，0，0，0} 

public class Solution1 {
    public static void main(String[] args) {
        int[] a = new int[5];
        System.out.println(a[3]+"--");

        for (int i=0;i<6;i++){
            a[3]++;
            System.out.println(a[3]);
        }
    }

}

https://blog.csdn.net/laoyao199044/article/details/93166776
https://my.oschina.net/fatwowzb/blog/208742