Question

关于我的程序的一些信息，我实现了一个带有单独链接的哈希表来处理冲突。

class TableInput{

     Object key;
     Object value;
     TableInput(Object key, Object value){
        this.key = key;
        this.value = value;
    }
}
abstract class HashTable {
    protected TableInput[] tableInput;
    protected int size;
    HashTable (int size) {
        this.size = size;
        tableInput = new TableInput[size];
        for (int i = 0; i <= size - 1; i++){
            tableInput[i] = null;
        }
    }
    abstract int hash(Object key);
    public abstract void insert(Object key, Object value);
    public abstract Object retrieve(Object key);
}
class ChainedTableInput extends TableInput {
    ChainedTableInput(Object key, Object value){
        super(key, value);
        this.next = null;
    }
     ChainedTableInput next;
}
 class ChainedHashTable extends HashTable {

    ChainedHashTable(int size) {
        super(size);
        // TODO Auto-generated constructor stub
    }
    public int hash(Object key){
        return key.hashCode() % size;

    }
    public Object retrieve(Object key){
        ChainedTableInput p;
        p = (ChainedTableInput) tableInput[hash(key)];
        while(p != null && !p.key.equals(key)){
            p = p.next;
        }
        if (p != null){
            return p.value;
        }
        else {
            return null;
        }
    }

    public void insert(Object key, Object value){
        ChainedTableInput entry = new ChainedTableInput(key, value);
        int k = hash(key);
        ChainedTableInput p = (ChainedTableInput) tableInput[k];
        if (p == null){
            tableInput[k] = entry;
            return;
        }
        while(!p.key.equals(key) && p.next != null){
            p = p.next;
        }
        if (!p.key.equals(key)){
            p.next = entry;
        }
    }
    public double distance(Object key1, Object key2){
        final int R = 6373;
        Double lat1 = Double.parseDouble(Object);

    }
    }

现在我有一个包含城市名称，纬度和经度的csv文件。我需要从命令行参数中读取csv文件，并将城市名称作为哈希表中的键输入，输入纬度和经度作为值。我的问题是如何读取csv文件并将数据分成要放入哈希表的键和值对象？

Answer 1

像这样 -

String csvFilePath = args[0];
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";

HashTable chainedHashTable = new ChainedHashTable(100);

try {
        br = new BufferedReader(new FileReader(csvFilePath));
        while ((line = br.readLine()) != null) {

                // use comma as separator
            String[] cityRow = line.split(cvsSplitBy);

            String cityName = cityRow[0];
            Double latitude = Double.parseDouble(cityRow[1]);
            Double longitude = Double.parseDouble(cityRow[2]);
            Coordinate coordinate = new Cordinate(latitude, longitude);

            chainedHashTable.insert(cityName, coordinate);

        }

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (NumberFormateException e) {
        e.printStackTrace();
    } finally {
        if (br != null) {
            try {
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }


class Coordinate {
    double latitude;
    double longitude;

    Coordinate (double latitude, double longitude) {
        this.latitude = latitude;
        this.longitude = longitude;
    }

    // Other setters and getters
}

读取csv文件并将行分隔为键和值以放入哈希表

1 个答案: