Can't seem to get .doubleValue () to work (I have latest Java version)
So, I am having a problem with a method I created called averageCost (). The error I am getting:
Exception in thread "main" java.lang.Error: Unresolved compilation problem:
The method doubleValue() is undefined for the type Double
at queue.averageCost(queue.java:38)
at queue.main(queue.java:47)
And earlier I tried to just add a double value to the Double object which obviously didn't work. So I found the .doubleValue method, but I can't seem to get it to work. I've added all my code (everything else works just fine) if it doesn't clear anything. I've been stuck on this for a couple of days while working on another, please help):
import java.util.LinkedList;
public class queue<Double> {
private LinkedList<Double> linklist;
private String symbol;
private String name;
private int shares;
private Double price;
public queue(String symbol2, String name2, int shares2, Double price2) { //so far, I have a linkedlist that works
linklist = new LinkedList<Double>();
shares = shares2;
price = price2;
symbol = symbol2;
name = name2;
bigAdd(shares, price);
}
public void add(Double e) {
linklist.add(e);
}
public Double take() {
return linklist.poll();
}
public void bigAdd (int shares2, Double price2) {
while(shares2>0) {
linklist.add(price2);
shares2--;
}
}
public double averageCost(int shares2) {
double average = 0;
int sizer = 0;
while(sizer < shares2) {
average = average + linklist.poll().doubleValue(); //this is where the problem lies
sizer++;
}
average = average/shares2;
return average;
}
}
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2 answers
Your error comes from the class declaration.
The generic formal parameter can be T:
public class queue<T> {
Now you can see that T does not have a method named doubleValue because you did not restrict it.
Then follow these steps:
import java.util.LinkedList;
public class queue<T extends Number> {
private final LinkedList<T> linklist;
private final int shares;
private final T price;
public queue( int shares2, T price2 ) {
linklist = new LinkedList<>();
shares = shares2;
price = price2;
bigAdd( shares, price );
}
public void add( T e ) {
linklist.add(e);
}
public T take() {
return linklist.poll();
}
public void bigAdd( int shares2, T price2 ) {
while(shares2>0) {
linklist.add(price2);
shares2--;
}
}
public double averageCost( int shares2 ) {
double average = 0;
int sizer = 0;
while( sizer < shares2 ) {
final T v = linklist.poll();
average = average + v.doubleValue();
sizer++;
}
average = average/shares2;
return average;
}
}
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