CODEWITHSUNDEEP
javacasting
klo
klo

Reputation: 95

Return generic type after parsing an Integer from a String

I am trying to write a method that gets an object from a database. This method must be able to specify what class that object expected to be (like: get("some.key", Integer.class) will return an integer). However, if the expected type is an integer, and our value is a string, I would like it to cast that string to an integer and return that. My current code looks like this:

public <T> T get(String key, Class<T> type) {
    Object element = ...;
    if (type == Integer.class && element instanceof String) return Integer.parseInt((String) element);
    return element;
}

However, my IDE is giving me an error: when returning Integer.parseInt((String) element), the method expects a return type of type T, but I am returning an Integer, which in that case is type T, but it won't accept this.

I have tried to cast it like so: (T) Integer.parseInt((String) element), but my IDE says that those are inconvertible types.

How can I make it so that this method will return a valid object of type T after parsing the Integer? Any help is appreciated.

Upvotes: 0

Views: 54

Answers (1)

erickson
erickson

Reputation: 269797

Cast your result to T using the Class instance you are passed.

public <T> T get(String key, Class<T> type) {
    Object element = ...;
    if (type == Integer.class && element instanceof String) element = Integer.parseInt((String) element);
    return type.cast(element);
}

Upvotes: 3

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