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我是 java 初学者，我在使用数组列表的二进制文件输入和输出时遇到问题。我正在尝试将数组列表中的数据存储在一个文件中，然后使用它在控制台中显示它。这是我的一些代码，它运行但显示错误信息，我也收到警告。对导致此问题的原因有任何帮助吗？谢谢！

public class Towers {
    public static ArrayList<String> allMoves= new ArrayList<String>();
    static{
        allMoves.add( "These Are the Disk Moves:" );
    }

    public static void move(final int aNumDisks){
        move(aNumDisks, 1, 2, 3);
        String fileName = "solution.dat";
        try{
            ObjectOutputStream outputStream = 
                    new ObjectOutputStream(
                            new FileOutputStream (fileName));
            outputStream.writeObject(allMoves);
            outputStream.close( );
        }
        catch ( IOException e ){
            System.out.println("Error writing to file " + fileName);
            System.exit(0);
        }
    }

在控制台中显示输出文件。

public class TReporter {        
    public static void reportSol(){
        String fileName = "solution.dat";
        ArrayList<String> allMovesA = null;
        try{
            ObjectInputStream inputStream =
                    new ObjectInputStream(
                            new FileInputStream (fileName));
            allMovesA = (ArrayList<String>)inputStream.readObject(); //WARNING!
                           //Type safety: Unchecked cast from Object to ArrayList<String>
            inputStream.close();
        }
        catch (Exception e){
            System.out.println("Problem reading the file " + fileName);
            System.exit(0);
        }
        for (int i = 0; i < allMovesA.size(); ++i){
            System.out.println( allMovesA.get(i) );
        }

它应该显示如下内容：

=== 0 disks move(int) ===
These Are the Disk Moves:

=== 0 disks move(,,) ===
These Are the Disk Moves:

=== 1 disk move(int) ===
These Are the Disk Moves:
Move disk from 1 to 3

=== 2 disks ===
These Are the Disk Moves:
Move disk from 1 to 2
Move disk from 1 to 3
Move disk from 2 to 3

=== 2 disks move(2,3,2,1) ===
These Are the Disk Moves:
Move disk from 3 to 2
Move disk from 3 to 1
Move disk from 2 to 1

=== 3 disks move(3) ===
These Are the Disk Moves:
Move disk from 1 to 3
Move disk from 1 to 2
Move disk from 3 to 2
Move disk from 1 to 3
Move disk from 2 to 1
Move disk from 2 to 3
Move disk from 1 to 3

但我得到了这个：

=== 0 disks move(int) ===
These Are the Disk Moves:
Move disk from 1 to 3
Move disk from 1 to 2
Move disk from 3 to 2
Move disk from 1 to 3
Move disk from 2 to 1
Move disk from 2 to 3
Move disk from 1 to 3

=== 0 disks move(,,) ===
These Are the Disk Moves:
Move disk from 1 to 3
Move disk from 1 to 2
Move disk from 3 to 2
Move disk from 1 to 3
Move disk from 2 to 1
Move disk from 2 to 3
Move disk from 1 to 3

=== 1 disk move(int) ===
These Are the Disk Moves:
Move disk from 1 to 3

=== 2 disks ===
These Are the Disk Moves:
Move disk from 1 to 2
Move disk from 1 to 3
Move disk from 2 to 3

=== 2 disks move(2,3,2,1) ===
These Are the Disk Moves:
Move disk from 1 to 2
Move disk from 1 to 3
Move disk from 2 to 3

=== 3 disks move(3) ===
These Are the Disk Moves:
Move disk from 1 to 3
Move disk from 1 to 2
Move disk from 3 to 2
Move disk from 1 to 3
Move disk from 2 to 1
Move disk from 2 to 3
Move disk from 1 to 3
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1 回答 1

2

您收到的警告是完全正常的。您可以通过在带有警告的行之前插入此行来抑制它：

@SuppressWarnings("unchecked")

对于您得到的错误信息：

  • 确保在尝试读取文件之前写入文件，您可能使用的是旧版本的文件。
  • 确保它确实包含正确的移动的 ArrayList。
于 2012-04-24T16:52:54.670 回答