Question

当我从教科书中运行此代码时。我收到以下错误：

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
    BagInterface cannot be resolved to a type
    ArrayBag cannot be resolved to a type
    ArrayBag cannot be resolved to a type
    at ArrayBagDemo1.main(ArrayBagDemo1.java:12)

以下是未编译的代码：

/**
A test of the methods add, toArray, and isFull, as defined
in the first draft of the class ArrayBag.
@author Frank M. Carrano
*/
public class ArrayBagDemo1
{
public static void main(String[] args)
{
   // a bag that is not full
   BagInterface<String> aBag = new ArrayBag<String>();
   // tests on an empty bag
   testIsFull(aBag, false);
   // adding strings
   String[] contentsOfBag1 = {"A", "A", "B", "A", "C", "A"};
   testAdd(aBag, contentsOfBag1);
   testIsFull(aBag, false);
   // a bag that will be full
   aBag = new ArrayBag<String>(7);
   System.out.println("\nA new empty bag:");
   // tests on an empty bag
   testIsFull(aBag, false);
   // adding strings
   String[] contentsOfBag2 = {"A", "B", "A", "C", "B", "C", "D"};
   testAdd(aBag, contentsOfBag2);
   testIsFull(aBag, true);
} // end main
// Tests the method add.
private static void testAdd(BagInterface<String> aBag, String[] content)
{
   System.out.print("Adding to the bag: ");
   for (int index = 0; index < content.length; index++)
   {
     aBag.add(content[index]);
     System.out.print(content[index] + " ");
   } // end for
System.out.println();
displayBag(aBag);
} // end testAdd
// Tests the method isFull.
// correctResult indicates what isFull should return.
private static void testIsFull(BagInterface<String> aBag,boolean correctResult)
{ 
   System.out.print("\nTesting the method isFull with ");
   if (correctResult)
     System.out.println("a full bag:");
   else
     System.out.println("a bag that is not full:");
   System.out.print("isFull finds the bag ");
   if (correctResult && aBag.isFull())
     System.out.println("full: OK.");
   else if (correctResult)
     System.out.println("not full, but it is full: ERROR.");
   else if (!correctResult && aBag.isFull())
     System.out.println("full, but it is not full: ERROR.");
   else
     System.out.println("not full: OK.");
} // end testIsFull
// Tests the method toArray while displaying the bag.
private static void displayBag(BagInterface<String> aBag)
{
   System.out.println("The bag contains the following string(s):");
   Object[] bagArray = aBag.toArray();
   for (int index = 0; index < bagArray.length; index++)
   {
     System.out.print(bagArray[index] + " ");
   } // end for
   System.out.println();
} // end displayBag
} // end ArrayBagDemo1

如何解决此问题以及错误意味着什么？

代码是对方法add，toArray和isFull的测试，如定义的那样在ArrayBag类的初稿中。

Answer 1

基于此，看起来您需要创建BagInterface和ArrayBag类，或者需要导入它们。

Answer 2

这意味着要么您没有创建类BagInterface，要么您没有导入它。 ArrayBag也是如此。您应该导入这些类

这是我教科书中的示例代码。它不会编译

2 个答案: