java 生成泛型的參數的實例 T t=new T()

方法1

ParameterizedType ptype = (ParameterizedType) this.getClass().getGenericSuperclass();
        Class clazz = (Class<T>) ptype.getActualTypeArguments()[0];
T o = (T) clazz.newInstance();

 

方法2

public class BaseViewModel<M extends Model> implements ViewModel {

    protected M model;

    private M createModel() {

        try {
            Type superClass = getClass().getGenericSuperclass();
            Type type = ((ParameterizedType) superClass).getActualTypeArguments()[0];
            Class<?> clazz = getRawType(type);
            return (M) clazz.newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    // type不能直接實例化對象，通過type獲取class的類型，然后實例化對象
    public static Class<?> getRawType(Type type) {
        if (type instanceof Class) {
            return (Class) type;
        } else if (type instanceof ParameterizedType) {
            ParameterizedType parameterizedType = (ParameterizedType) type;
            Type rawType = parameterizedType.getRawType();
            return (Class) rawType;
        } else if (type instanceof GenericArrayType) {
            Type componentType = ((GenericArrayType) type).getGenericComponentType();
            return Array.newInstance(getRawType(componentType), 0).getClass();
        } else if (type instanceof TypeVariable) {
            return Object.class;
        } else if (type instanceof WildcardType) {
            return getRawType(((WildcardType) type).getUpperBounds()[0]);
        } else {
            String className = type == null ? "null" : type.getClass().getName();
            throw new IllegalArgumentException("Expected a Class, ParameterizedType, or GenericArrayType, but <" + type + "> is of type " + className);
        }
    }

}
//上面這個getRawType方法研究了很久，最后查看了Gson的源碼發現了這段代碼的寫法，現分享給大家，希望有幫助。