Question

我有以下用于android geofencing的课程：

public class gpsLocationChecker {

    List<ArrayList<location>> locations = new ArrayList<ArrayList<location>>();

    //public location locations[][] = new location[8][500];

    InputStream in;
    String[] oblastiGPSArray;

    public gpsLocationChecker(InputStream in, String[] oblastiGPSArray){
        this.in = in;
        this.oblastiGPSArray = oblastiGPSArray;
        try {
            loadParser();
        }catch(Exception e){}
    }

    public String findPoint(Double Long, Double Lat){
        for(int i = 0; i <= locations.size(); i++){
            if(PointIsInRegion(Long, Lat, locations.get(i)))
            {
                return(oblastiGPSArray[i]);
            }
        }
        return "abc";
    }
    private boolean PointIsInRegion(double x, double y, ArrayList<location> oblast)
    {
        int crossings = 0;

        location point = new location (x, y);
        int count = oblast.size();
        // for each edge
        for (int i=0; i < count; i++)
        {
            location a = oblast.get(i);
            int j = i + 1;
            if (j >= count)
            {
                j = 0;
            }
            location b = oblast.get(j);
            if (RayCrossesSegment(point, a, b))
            {
                crossings++;
            }
        }
        // odd number of crossings?
        return (crossings % 2 == 1);
    }
    boolean RayCrossesSegment(location point, location a, location b)
    {
        double px = point.Long;
        double py = point.Lat;
        double ax = a.Long;
        double ay = a.Lat;
        double bx = b.Long;
        double by = b.Lat;
        if (ay > by)
        {
            ax = b.Long;
            ay = b.Lat;
            bx = a.Long;
            by = a.Lat;
        }
        // alter longitude to cater for 180 degree crossings
        if (px < 0) { px += 360; };
        if (ax < 0) { ax += 360; };
        if (bx < 0) { bx += 360; };

        if (py == ay || py == by) py += 0.00000001;
        if ((py > by || py < ay) || (px > Math.max(ax, bx))) return false;
        if (px < Math.min(ax, bx)) return true;

        double red = (ax != bx) ? ((by - ay) / (bx - ax)) : Float.MAX_VALUE;
        double blue = (ax != px) ? ((py - ay) / (px - ax)) : Float.MAX_VALUE;
        return (blue >= red);
    }
    private void loadParser() throws XmlPullParserException, IOException {
        try {
            XmlPullParser parser = Xml.newPullParser();
            parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
            parser.setInput(in, null);
            loadData(parser);
        } finally {
            in.close();
        }
    }
    private void loadData(XmlPullParser parser) throws XmlPullParserException, IOException {
        int eventType = parser.getEventType();
        while (eventType != XmlPullParser.END_DOCUMENT){
            int x = 0;
            if(eventType == XmlPullParser.START_TAG){
                if(parser.getName() == "coordinates"){
                    String coordinates = parser.nextText();
                    StringTokenizer st = new StringTokenizer(coordinates, ",", false);
                    int y = 0;
                    locations.get(x).add(y, new location(Double.parseDouble(st.nextToken()), Double.parseDouble(st.nextToken())));
                    while(st.hasMoreTokens()){
                        y++;
                        locations.get(x).add(y, new location(Double.parseDouble(st.nextToken().substring(2)), Double.parseDouble(st.nextToken())));
                    }
                    x++;
                }
            }
            eventType = parser.next();
        }
    }
}

如果我尝试运行它，它会对此代码if(PointIsInRegion(Long, Lat, locations.get(i)))抛出indexOutOfBoundException我确信XML正确解析。我无法看到任何错误，但我认为这将是我的2D arraylist（我第一次使用它）。我真的很绝望。你能告诉我我做错了什么吗？

先谢谢

Answer 1

for(int i = 0; i <= locations.size(); i++){时

i = locations.size()将超出范围。

更改为for (int i=0; i<locations.size(); i++) {。

Android：2d arraylist返回indexoutofbounds

1 个答案: