My code doesn't seem to work when the string token is an int. Here it is:

public class CO2Data {

    CO2Data dataSet[] = new CO2Data[10];
    String strLine = "Italy 476.08  116.86  2   592";
    int lines = 10;
    double roadCO2;

    public void saveLineInfo(String strLine, int lines) {
        StringTokenizer token = new StringTokenizer(strLine);
        String str = "hello";
        int count = 0;
        for (int i = 0; i < lines; i++) {
            while (token.hasMoreTokens()) {
                str = token.nextToken();
                if (count == 3) {
                    getRoadCO2(str, roadCO2);
                    dataSet[i].setRoadCO2(roadCO2);
                }
                count++;
            }
        }
    }

    public double getRoadCO2(String str, double roadCO2) {
        roadCO2 = Double.parseDouble(str);
        return roadCO2;
    }

    public void setRoadCO2(double roadCO2) {
        this.roadCO2 = roadCO2;
    }
}

In the rest of the lines, roadCO2 is a double, so I'm guessing my program is getting confused? How do I fix it? Thanks so much!

• java
• parsing

You are getting NullPointerException because,

You've declared an Array of CO2Data dataSet[] = new CO2Data[10];, but every element inside this CO2Data[] array is pointing to Null.

Hence, this call: dataSet[i].setRoadCO2(roadCO2); will generate a NullPointerException because dataSet[i] is pointing to null.

Solution :

Instantiate dataSet[i] = new CO2Data(); then call dataSet[i].setRoadCO2(roadCO2);

I'd recommend changing the names of the parameters to your methods to something slightly different than the class datamember "roadCO2". That might help you sort out the error :)

When I ran your code, I got a NullPointerException at line 22. This is beacuse the array 'data' has not been initialized.

You can initialize your array as follows

for(int i = 0; i < dataSet.length; i++) {
    dataSet[i] = new CO2Data();
}