ArrayList：java.lang.IndexOutOfBoundsException：索引：283，大小：283 [重复]

Question

我编写了一个算法来计算一辆车跟随的轨道距离。轨道上的每个点都有一个（纬度，经度）。这是我的代码，我收到了上面提到的错误。

List<TrackPoint> tp = new ArrayList<TrackPoint>();    

for (int i = 0; i < tp.size(); i++) {
    double lat1 = tp.get(i).getLat();                        
    double lat2 = tp.get(i + 1).getLat();
    double lon1 = tp.get(i).getLon();                       
    double lon2 = tp.get(i + 1).getLon();
    double radlat1 = Math.PI * lat1 / 180;
    double radlat2 = Math.PI * lat2 / 180;
    double theta = lon1 - lon2;
    double radtheta = Math.PI * theta / 180;
    double dist = Math.sin(radlat1) * Math.sin(radlat2) + Math.cos(radlat1) * Math.cos(radlat2) * Math.cos(radtheta);
    dist = Math.acos(dist);
    dist = dist * 180 / Math.PI;
    dist = dist * 60 * 1.1515; 
    dist = dist * 1609.344;// distance in miles
    double _KM = 1000; //KM the unit of distance                       
    //distance in km
    double distInKM = dist / _KM;
    DecimalFormat df = new DecimalFormat("###.###");
    double dt = Double.parseDouble(df.format(distInKM));
    double mileage = 0;
    mileage += mileage + dt;       
    tp.get(i).setMileage(mileage);                       
}

错误：

java.lang.IndexOutOfBoundsException: Index: 283, Size: 283
    at java.util.ArrayList.rangeCheck(ArrayList.java:653)
    at java.util.ArrayList.get(ArrayList.java:429)

此错误指向行：double lat2 = tp.get(i + 1).getLat(); 我认为错误与列表大小有关，但我不知道为什么？有人帮我看看我有什么问题。

Answer 1

当您转到循环中的最后一个对象 (TrackPoint) 时，i + 1 元素不存在。

double lat2 = tp.get(i + 1).getLat();

Answer 2

问题来了

tp.get(i + 1)

当i 等于tp.size-1 时，你使它等于tp.size()。为了解决它，将 for 循环更改为：

for (int i = 0; i < tp.size() - 1; i++) {

Answer 3

当您转到循环中的最后一个对象 (TrackPoint) 时，第 (i + 1) 个元素不存在。希望下面的代码没问题。

List<TrackPoint> tp = new ArrayList<TrackPoint>();    

for (int i = 0; i < tp.size()-1; i++) {
    double lat1 = tp.get(i).getLat();                        
    double lat2 = tp.get(i + 1).getLat();
    double lon1 = tp.get(i).getLon();                       
    double lon2 = tp.get(i + 1).getLon();
    double radlat1 = Math.PI * lat1 / 180;
    double radlat2 = Math.PI * lat2 / 180;
    double theta = lon1 - lon2;
    double radtheta = Math.PI * theta / 180;
    double dist = Math.sin(radlat1) * Math.sin(radlat2) + Math.cos(radlat1) * Math.cos(radlat2) * Math.cos(radtheta);
    dist = Math.acos(dist);
    dist = dist * 180 / Math.PI;
    dist = dist * 60 * 1.1515; 
    dist = dist * 1609.344;// distance in miles
    double _KM = 1000; //KM the unit of distance                       
    //distance in km
    double distInKM = dist / _KM;
    DecimalFormat df = new DecimalFormat("###.###");
    double dt = Double.parseDouble(df.format(distInKM));
    double mileage = 0;
    mileage += mileage + dt;       
    tp.get(i).setMileage(mileage);                       
}

Answer 4

您循环迭代直到列表大小。但在最后一次迭代中，您试图获取 (i + 1) 索引在您的情况下不存在。

double lat2 = tp.get(i + 1).getLat();

更正这个 .get(i + 1)。

Answer 5

以上所有答案都是正确的。或者可以尝试使用以下代码

List<TrackPoint> tp = new ArrayList<TrackPoint>();
    for (int i = 0; i < tp.size(); i++) {
    double lat1 = tp.get(i - 1).getLat();                        
    double lat2 = tp.get(i).getLat();
    double lon1 = tp.get(i - 1).getLon();                       
    double lon2 = tp.get(i).getLon();
    double radlat1 = Math.PI * lat1 / 180;
    double radlat2 = Math.PI * lat2 / 180;
    double theta = lon1 - lon2;
    double radtheta = Math.PI * theta / 180;
    double dist = Math.sin(radlat1) * Math.sin(radlat2) + Math.cos(radlat1) * Math.cos(radlat2) * Math.cos(radtheta);
    dist = Math.acos(dist);
    dist = dist * 180 / Math.PI;
    dist = dist * 60 * 1.1515; 
    dist = dist * 1609.344;// distance in miles
    double _KM = 1000; //KM the unit of distance                       
    //distance in km
    double distInKM = dist / _KM;
    DecimalFormat df = new DecimalFormat("###.###");
    double dt = Double.parseDouble(df.format(distInKM));
    double mileage = 0;
    mileage += mileage + dt;       
    tp.get(i - 1).setMileage(mileage);
}