java将Scanner转换为两个ArrayList，一个带有double，另一个带有String

Question

String dataSourceString = "String  43\n String1   50\n String2   45";
Scanner dataSource = new Scanner(dataSourceString);
ArrayList<String> scanString = new ArrayList<String>();
ArrayList<Double> scanDoubleValue = new ArrayList<Double>();
while(dataSource.hasNextLine()) {
    scanString.add(dataSource.next());
    String stringToDouble = dataSource.next();
    Double doubleValue = stringToDouble.parseDouble();
    scanDoubleValue.add(doubleValue);
}

最终目标是将"String Double"格式的值列表转换为TreeMap<String, ArrayList<Double>> map = new TreeMap<>();格式的树映射

我一直在写一个循环来分离这两种对象类型

Answer 1

试试这个：

import java.util.*;
import java.util.List;
import java.lang.Double;

public class DeleteFromList {

   public static void main(String[] args) {

   String dataSourceString = "String  43\n String1   50\n String2   45";
      Scanner dataSource = new Scanner(dataSourceString);
      ArrayList<String> scanString = new ArrayList<String>();
      ArrayList<Double> scanDoubleValue = new ArrayList<Double>();
      while(dataSource.hasNextLine()) {
          scanString.add(dataSource.next());
          String stringToDouble = dataSource.next();
          //your line hase the following and I changed it
          //Double doubleValue = stringToDouble.parseDouble();
          Double doubleValue = Double.parseDouble(stringToDouble);
          scanDoubleValue.add(doubleValue);
      }
      System.out.println(scanString);
      System.out.println(scanDoubleValue);
   }

}

Answer 2

假设值列表用于重复项，为什么不直接写入映射

String dataSourceString = "String  43\n String1   50\n String2   45";
Scanner dataSource = new Scanner(dataSourceString);
ArrayList < String > scanString = new ArrayList < String > ();
ArrayList < Double > scanDoubleValue = new ArrayList < Double > ();
Map < String, List < Double >> map = new TreeMap <> ();
while (dataSource.hasNextLine()) {
    String key = dataSource.next();
    Double value = Double.parseDouble(dataSource.next());
    if (map.containsKey(key)) {
        map.get(key).add(value);
    } else {
        List < Double > valueList = new ArrayList();
        valueList.add(value);
        map.put(key, valueList);
    }

}