Question

我正在使用Google图表API和 Google Visualization Candlestick Charts期望数据是一个数组数组，以便它可以工作。

例如以下格式

[
[ "2011-08-01", 136.65, 136.96, 134.15, 136.49 ],
[ "2011-08-02", 135.26, 135.95, 131.50, 131.85 ],
[ "2011-08-05", 132.90, 135.27, 128.30, 135.25 ]
]

这是我通过数据库检索数据的SQL

String selectsql = "select current_day ,  open_val , high_val , low_val , close_val  from   historical_data where symbol_name = ?";
while(Rset.next())
            {
                String current_day =  SgxRset.getString("current_day");
                String open_val =  SgxRset.getString("open_val");
                String high_val =  SgxRset.getString("high_val");
                String low_val =  SgxRset.getString("low_val");
                String close_val =  SgxRset.getString("close_val");
            }

您能否告诉我如何构建如何构造数组？

示例程序

import java.util.ArrayList;
import java.util.List;

import org.json.JSONException;

public class TestJSON {

    public static void main(String[] args) throws JSONException {
        Employee emp1 = new Employee();
        emp1.setName("Ravi");
        emp1.setName("20");
        Employee emp2 = new Employee();
        emp2.setName("Kiran");
        emp2.setName("20");
        List<Employee> histList = new ArrayList<Employee>();

         Object[] arrayResultData = histList.toArray();

    }
}


public class Employee {

    String name ;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    String age ;

}

Answer 1

I recommend a List. You don't know what your columns are and how many you have:

List<HistData> histList = new ArrayList<HistData>();
//.. query db
while(Rset.next()){
  HistData histData = new HistData();
  histData.setCurrentDay( SgxRset.getString("current_day"));
  histData.setOpenVal( SgxRset.getString("open_val"));
  histData.setHighVal( SgxRset.getString("high_val"));
  histData.setLowVal( SgxRset.getString("low_val"));
  histData.setCloseVal( SgxRset.getString("close_val"));
  histList.add(histData);
}

HistData is just a POJO，但您可以更改bean和SgxRset检索类型中的数据类型，这样您就不会被锁定到任何数组类型。使用List而不是数组可以在返回许多未知长度的结果时提供更大的灵活性。

public class HistData {
    public HistData(){}
    String currentDay;
    public setCurrentDay(String currentDay){
        this.currentDay = currentDay;
    }
    public getCurrentDay(){
        return currentDay;
    }
    // .. etc.
}

Answer 2

使用getter和setter创建一个将所有这些数据保存在这样的对象中的类：

 public class Data {
            private String current_day;
    private double open_val;
    private double high_val;
    private double low_val;
    private double close_val;

    public Data(String current_day, double open_val, double high_val,
            double low_val, double close_val) {
        this.current_day = current_day;
        this.open_val = open_val;
        this.high_val = high_val;
        this.low_val = low_val;
        this.close_val = close_val;
    }

    public String getCurrent_day() {
        return current_day;
    }

    public void setCurrent_day(String current_day) {
        this.current_day = current_day;
    }

    public double getOpen_val() {
        return open_val;
    }

    public void setOpen_val(double open_val) {
        this.open_val = open_val;
    }

    public double getHigh_val() {
        return high_val;
    }

    public void setHigh_val(double high_val) {
        this.high_val = high_val;
    }

    public double getLow_day() {
        return low_val;
    }

    public void setLow_day(double low_day) {
        this.low_val = low_day;
    }

    public double getClose_day() {
        return close_val;
    }

    public void setClose_day(double close_day) {
        this.close_val = close_day;
    }

    }

现在，将数据存储在您从SQL获取的对象数组中。

String selectsql = "select current_day ,  open_val , high_val , low_val ,close_val  from   historical_data where symbol_name = ?";
    List<Data> myList = new ArrayList(Data); 
    while(Rset.next())
                {
                    String current_day =  SgxRset.getString("current_day");
                    String open_val =  SgxRset.getString("open_val");
                    String high_val =  SgxRset.getString("high_val");
                    String low_val =  SgxRset.getString("low_val");
                    String close_val =  SgxRset.getString("close_val");

                    Data data = new Data(current_day,open_val,high_val,low_val,close_val);
                    myList.add(data);
                }

对于阅读数据，您可以写：

 String a = "[ ";
    for (int i = 0; i < myList.size(); i++) {
        String b = "[ \"" + myList.get(i).getCurrent_day() + "\" , "
                + myList.get(i).getOpen_val() + "],";
        if(i==myList.size() -1)
            a += b;
        else
            a += b+",";
    }
    a += " ]";

现在，对我来说输出是：

[ [ "2011-08-01" , 136.65],[ "2011-08-02" , 135.26] ]

Answer 3

使用List和toArray方法

String selectsql = "select current_day ,  open_val , high_val , low_val ,     close_val  from   historical_data where symbol_name = ?";

      List<String[]>resultData = new ArrayList<Stirng[]>();

        while(Rset.next())
                {
                    String[] array = new String[5];

                    array[0] =  SgxRset.getString("current_day");
                    array[1] =  SgxRset.getString("open_val");
                    array[2] =  SgxRset.getString("high_val");
                    array[3] =  SgxRset.getString("low_val");
                    array[4] =  SgxRset.getString("close_val");
                }

        Object[] arrayResultData = resultData.toArray();

如何从Resultset构造数组数组

3 个答案: