Java: Combine 2 List <String[]>
I have two List of array string. I want to be able to create a New List (newList) by combining the 2 lists. But it must meet these 3 conditions:
1) Copy the contents of store_inventory into newList.
2) Then if the item names in store_inventory & new_acquisitions match, just add the two quantities together and change it in newList.
3) If new_acquisitions has a new item that does not exist in store_inventory, then add it to the newList.
The titles for the CSV list are: Item 开发者_如何学JAVAName, Quantity, Cost, Price.
The List contains an string[] of item name, quantity, cost and price for each row.
CSVReader from = new CSVReader(new FileReader("/test/new_acquisitions.csv"));
List <String[]> acquisitions = from.readAll();
CSVReader to = new CSVReader(new FileReader("/test/store_inventory.csv"));
List <String[]> inventory = to.readAll();
List <String[]> newList;
Any code to get me started would be great! =]
this is what i have so far...
for (int i = 0; i < acquisitions.size(); i++) {
temp1 = acquisitions.get(i);
for (int j = 1; j < inventory.size(); j++) {
temp2 = inventory.get(j);
if (temp1[0].equals(temp2[0])) {
//if match found... do something?
//break out of loop
}
}
//if new item found... do something?
}
I would start by building the newList as a HashMap or TreeMap instead of a List. This makes it easy to search for the matching record. Furthermore, I would convert the String[] to a custom object (e.g. Record) that contains the name, quantity, cost and price field. This would take care of copying the information. The you could try something like this:
Map<String, Record> newMap = new TreeMap<String, Record>();
for(String[] ss : acquisitions) {
Record rec = Record.parse(ss); // For requirement (1)
newMap.put(rec.getName(), rec);
}
for(String[] ss : inventory) {
Record rec = Record.parse(ss); // For requirement (1)
if(newMap.containsKey(rec.getName())) {
// For requirement (2)
// The mergeWith method can then add quantities together
newMap.get(rec.getName()).mergeWith(rec);
} else {
// For requirement (3)
newMap.put(rec.getName(), rec);
}
}
edit
An extra advantage of having a Record object, is that it can be printed to screen much easier by implementing the toString
function.
public class Record implements Comparable<Record> {
public static Record parse(String[] ss) {
// TODO: implement some basic parsing
}
private String name;
private int quantity;
private BigDecimal cost, price;
private Record() {}
public String getName() { return name; }
public int getQuantity() { return quantity; }
public BigDecimal getCost() { return cost; }
public BigDecimal getPrice() { return price; }
public int compareTo(Record other) {
return this.name.compareTo(other.name);
}
public String toString() {
return name;
}
}
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