I have a method
public static <T> T createObject(Class<T> t){
}
You see, I want to get a instance of T.
I know this can be realized, because:
public <T> T find(Object id, Class<T> type) {
return (T) this.em.find(type, id);
}
Help me........
If the class t has a no-args constructor, then the Class.newInstance() method will do what is needed:
public static <T> T createObject(Class<T> t)
throws InstantiationException, IllegalAccessException {
return t.newInstance();
}
Note that you have to either propagate or deal with checked exceptions arising from things like:
t object represents an interface or an abstract class,t class doesn't have a no-args constructor, ort class or its no-args constructor are not accessible.siunds like you need reflection
import java.reflect.*; ... Class klass = obj.class; Object newObj = klass.newInstance(); return (T)newObj;
note: written from memory, so the api may be slightly different.
If you want manage parameters, you can do that :
public static <T> T instantiate(Class<T> clazz, Object ... parameters) throws Exception {
Validate.notNull(clazz, "Argument 'clazz' null!");
if (!ArrayUtils.isEmpty(parameters)) {
Class<?> [] parametersType = new Class<?>[parameters.length];
for(int i=0 ; i<parameters.length ; i++) {
parametersType[i] = parameters[i].getClass();
}
return clazz.getConstructor(parametersType).newInstance(parameters);
}
return clazz.newInstance();
}
