不能初始化泛型参数和数组

class Foo<T>{
    //private T t =new T();//报错Cannot instantiate the type T
    //private T[] tArray= new T[5];//报错Cannot create a generic array of T
    private List<T> list= new ArrayList<T>();
}

 1 public class ArrayList<E> extends AbstractList<E>
 2         implements List<E>, RandomAccess, Cloneable, java.io.Serializable{
 3     /**
 4      * The array buffer into which the elements of the ArrayList are stored.
 5      * The capacity of the ArrayList is the length of this array buffer.
 6      */
 7     private transient Object[] elementData;
 8     /**
 9      * Constructs an empty list with an initial capacity of ten.
10      */
11     public ArrayList() {
12         this(10);
13     }    
14         
15     /**
16      * Returns the element at the specified position in this list.
17      *
18      * @param  index index of the element to return
19      * @return the element at the specified position in this list
20      * @throws IndexOutOfBoundsException {@inheritDoc}
21      */
22     public E get(int index) {
23         rangeCheck(index);
24 
25         return elementData(index);
26     }
27     E elementData(int index) {
28         return (E) elementData[index];
29     }        
30 }

 1 import java.lang.reflect.Array;
 2 import java.util.ArrayList;
 3 import java.util.List;
 4 
 5 public class Client {
 6     public static void main(String[] args) {
 7         
 8         
 9     }
10 }
11 
12 class Foo<T>{
13     //不再初始化，由构造函数初始化
14     private T t;
15     private T[] tArray;
16     private List<T> list= new ArrayList<T>();
17     //构造函数初始化
18     public Foo(){
19         try {
20             Class<?> tType = Class.forName("");
21             t = (T)tType.newInstance();
22             tArray = (T[])Array.newInstance(tType,5);
23         } catch (Exception e) {
24             e.printStackTrace();
25         }
26     
27     }
28 }