Re: How to create an instance of type T?

Daniel Pitts <>
Sat, 23 Feb 2008 08:34:32 -0800
Joshua Cranmer wrote:

prowyh wrote:

I want to write a generic method that return the specified object
constructed with type parameter T and the parameter of type String.


class GClass<T>
    public T getValue(String p) throws Exception
        // create and instance of type T or a Class class of type T
        // construct the object with p by reflection
        // return the object

You'll need to modify the code here somewhat:
class GClass<T> {
    private Class<T> clazz;

    public GClass<T>(Class<T> clazz) {
        this.clazz = clazz;

    public T getValue(String p) throws Exception {
        return clazz.getConstructor(String.class).newInstance(p);

Beware: reflection is slow.

Not *that* slow. Granted, slower than normal object instantiation, but
every Java release they seem to enhance the speed of reflection.

Daniel Pitts' Tech Blog: <>

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