单链表 - 无法对静态类型进行静态引用

Question

我正在使用单向链表来学习Java。

我有一个工作链表，但它绑定到整数类型，我现在想通过改变所有的整数声明泛型类型E.

编译器不断抱怨说，它“实现一个通用的类型化链表无法对非静态类型E“进行静态引用。代码仍然运行。有谁知道如何解决这个错误“？

我认为这是与一般的E型是静态像整数或双或如果它是像字符串或其他类的引用类型。

public class TestingLinkedList<E> { 


private E value; 
private TestingLinkedList<E> next; 

/* 
* Default Constructor 
* 
* @param value an absolute E value for the current Node 
* 
* @param next an absolute RecursiveLinkedList value for the current Node 
*/ 
public TestingLinkedList(E value, TestingLinkedList next) { 
    this.value = value; 
    this.next = next; 
} 

/* 
* Constructor Empty, when user supplies an empty for the constructor uses 
* value = - 1 and next = null as input parameters 
* 
* @param value an absolute int value for the current Node 
* @param next an absolute RecursiveLinkedList value for the current Node 
*/ 
public static final TestingLinkedList EMPTY = new TestingLinkedList(null,null) 
{ 
    public TestingLinkedList remove(E n) { 
     return this; 
    }; 

    public String toString() { 
     return ""; 
    }; 
}; 

/* 
* if the current node is null return false 
* else if current value is the chosen value 
* then return true. Otherwise call the contains 
* method of the next item in queue 
* 
* @param value an absolute int value for the current Node 
* @param RecursiveLinkedList object of the remove item 
* */ 
public TestingLinkedList remove(E n) { 
    if (value == n) { 
     return next; 
    } 
    // Call the remove method of the next Node if the selected Node is not 
    // the current node then construct and return the next method 
    return new TestingLinkedList(value, next.remove(n)); 
} 

/* 
* if the current node is null return false 
* else if current value is the chosen value 
* then return true. Otherwise call the contains 
* method of the next item in queue 
* 
* @param value an absolute int value for the current Node 
* @param boolean 
* */ 
public boolean contains(E n) { 
    if (next == null) { 
     return false; 
    }else if (value == n) { 
     return true; 
    } else { 
     return next.contains(n); 
    } 
} 

public String toString() { 
    return value + "," + next.toString(); 
} 


/* 
* 
* Testing Methods for RecursiveLinkedList 
* 
* */ 
public static void main(String[] args) { 
    TestingLinkedList l = new TestingLinkedList(1, 
      new TestingLinkedList(2, new TestingLinkedList(2, 
        new TestingLinkedList(3, new TestingLinkedList(4, 
          EMPTY))))); 
    System.out.println(" Test to String Method : " + l.toString()); 
    System.out.println(" Test remove method " + l.remove(1).toString()); 
    System.out.println(" Test contains method " 
      + String.valueOf(l.contains(4))); 
} 

}

Answer 1

public static final TestingLinkedList EMPTY = new TestingLinkedList(null,null) 

应该是：

public static final TestingLinkedList<Integer> EMPTY 
             = new TestingLinkedList<Integer>(null,null) 

这违反了基因因为E的占位符是在施工时确定的，并且这是静态的，所以它不能使用E值。请使用通用方法：

public static <T> TestingLinkedList<T> empty() { 
    return new TestingLinkedList<T>(null, null) { 

     public TestingLinkedList remove(T n) { 
      return this; 
     } 

     public String toString() { 
      return ""; 
     } 
    } 
}