错误：< 运算符未定义参数类型 Double[], double

Question

I know this is quite basic but I am having trouble understanding to use < when testing against objects in an array.

I want to test the ruleGrades which are stored in an 2D array against minimum (a double ), and then multiply it with a probability ( double ).

ArrayList<Double[][]> ruleGrades  = new ArrayList<Double[][]>();
ArrayList<Double> min= new ArrayList<Double>();
double minimum;

System.out.println("Rule Grades: "+ruleGrades.toString());
        for(int a=0;a<ruleGrades.size();a++)
        {
            minimum=2.0;
            System.out.println("A: "+a);
            for(Double[] grades : ruleGrades.get(a))
            {
                if(grades<minimum) //error over here
                {
                    Double prob=rule.getRules().get(a).getProbability();
                    minimum=grades.doubleValue()*prob.doubleValue(); //error  
                }
            }
            min.add(minimum);
        }
        max=0.0; //finding largest
        for (int b = 0; b< min.size(); b++ )
        {
            if( min.get(b) > max)
            {
                max = min.get(b);
            }
        }
    }

UPDATE:

Okay I see that i dont need a multidimensional array, I can just use a Double[] to have 2 values in the first element. Here is my updated code:

ArrayList<Double[]> ruleGrades  = new ArrayList<Double[]>();
ArrayList<Double[]> min= new ArrayList<Double[]>();


System.out.println("Rule Grades: "+ruleGrades.toString());
        for(int a=0;a<ruleGrades.size();a++)
        {
            Double [] minimum={2.0,2.0};
            System.out.println("A: "+a);
            for(Double grades : ruleGrades.get(a))
            {
                if(grades<minimum[0])
                {
                    Double prob=rule.getRules().get(a).getProbability();
                    minimum[0]=grades.doubleValue()*prob.doubleValue();
                }
                if(grades<minimum[1])
                {
                    Double prob=rule.getRules().get(a).getProbability();
                    minimum[1]=grades.doubleValue()*prob.doubleValue();
                }
            }
            min.add(minimum);
        }
        Double [] max= {0.0,0.0}; //finding largest
        for (int b = 0; b< min.size(); b++ )
        {
            for(Double mins : min.get(b))
            {
                if( mins> max[0])
                {
                    max = min.get(b);
                }
            }   
        }
    }

So in my first IF statement I want to check if the first double is less than 2.0, then multiple it by the probability and then add it to the arraylist min.

But how would I do that for the second value in the same element. For example ruleGrades contains: [1.7,1.9],[1.2,1.3] .... Then i take 1.7 multiply by prob (lets just say its 1) and add to the Double[] in the min arraylist, so min will look like this [1,7]. But then I wish to the same for 1.9 and put it in the same element as 1.7, so then the min array will look like [1.7,1.9]. Thats why i have added another IF statement , is this correct?

After all the grades have been multiplied by the prob and added to the min arraylist, i need to find the biggest one. So i made a Double max[] is that correct ?

Sorry about this, I am trying to read but I am really confused. Thanks for all the help so far.

Answer 1

Actually you have declared array in inner for loop and comparing the whole array to a single double value.

grades < minimum is the problem

for(Double[] grades : ruleGrades.get(a))
{
    if(grades is an array of Double < minimum is a double )  //error over here
     {