Java – NullPointerException when accessing array in class

I am new to this forum and Java The following code compiles, but when I try to enter a value for a variable, I get NullPointerException What's up?

class output_harm
{
    public int[] timestamp;
    public int[] state;

    public output_harm(){
        timestamp = new int[8];
        state = new int[8];
    }
}

output_harm[][] outputs =  new output_harm[7][6];   

outputs[0][0].state[0] = 0; //java.lang.NullPointerException

Solution

problem

This is just initializing an array When you call the constructor output_ When harm(), it only initializes state = new int [8]; The state here is initialized in the constructor and results in NullPointerException

Solution: first of all, you need to create a_ Harm initializes an object (if you need to initialize the entire array)

output_harm[][] outputs =  new output_harm[7][6];   
    for(int i=0;i<7;i++){
        for(int j=0;j<6;j++){
            outputs[i][j] = new output_harm();
        }
    }

    outputs[0][0].state[0] = 1;