Nested Collection Based Loops

ckeveny · February 14th, 2013, 03:46 AM

See page 124.
I want to loop through my 2 dimensional by nesting a collection based for loop within another collection based for loop.
In the book we create:
float[][] temp = new float [10][365]; //we fill this 2D Array with random float values

//I want an outer loop to go through the 1st dimension and the inner loop to go through the 2nd dimension:

float average = 0;
for(float[] locations:temperature){//cycle through the outer loop
for(float[] temps:temperature[locations]){//cycle through the inner loop
average += temps;
}
System.out.println(average);
average = 0;
}

The inner loop returns an error saying an int is required not a float[]

ckeveny · February 14th, 2013, 12:10 PM

It's not so much going through the collection based for loop that I can't figure out, I have that, it's nesting them inside each other and accessing the elements in the 2nd dimension with the inner loop that I can't figure out.

ckeveny · February 15th, 2013, 12:52 AM

// I got it, the inner loop is just float not float[]
// I was trying to go too many dimensions deep in the inner loop
// that took 90 minutes to figure out

Code:

public class WeatherFan2{
    static int count = 0;
    static float average = 0;

    public static void main(String[]args){
        float[][] sample = new float[10][10];
        for(int x = 0;x<10;x++){
            for(int y = 0;y<10;y++){
                sample[x][y]= (float)((Math.random()*100)+1);
                
            }
        }
        //we now have a 10x10 2D array
        loop:
        for(float[] temperature:sample){
            for(float t:temperature){
                average +=t;
            }
            System.out.println(average/sample[count].length);       
        average =0;
        }
    }
}