對象無法正常讀取

我正在編寫一個程序，將一個數組對象寫入一個java二進制文件，然後將其讀回。問題是當數組讀入數組時，它正在返回[null，null ]。我沒有正確地讀/寫對象嗎？對象無法正常讀取

DBMS.java

public static void writeToFile(Datab[] friends) { 
    try { 
     ObjectOutputStream myStream = new ObjectOutputStream(
       new FileOutputStream("datt.dat")); 
     for(int i=0; i<friends.length; i++){ 
     myStream.writeObject(friends[i]); 
     } 
     myStream.close(); 
    } 
    catch (FileNotFoundException e) { 
    } catch (IOException e) { 
    } 

    System.out.println("\n\nArray written to file datt."); 
} 

/********************************************************** 
* readFromFile Read from the binary file and return the array of objects to 
* the calling method Catch the following exceptions: FileNotFoundException, 
* ClassNotFoundException, and the IOException (know what each does!) 
* 
* @return The array as read in from the binary input file 
*/ 
public static Datab[] readFromFile() { 
    System.out 
      .println("\n\nNow let's reopen the file and display the array."); 
    Datab[] b = null; 

    // The name of the file to open. 
    String fileName = "datt.dat"; 

    try { 
     // Use this for reading the data. 
     byte[] buffer = new byte[1000]; 

     ObjectInputStream input = new ObjectInputStream(new FileInputStream("datt.dat")); 

     input.close(); 

    } catch (FileNotFoundException ex) { 
     System.out.println("Unable to open file '" + fileName + "'"); 
    } catch (IOException ex) { 
     System.out.println("Error reading file '" + fileName + "'"); 
     // Or we could just do this: 
     // ex.printStackTrace(); 
    } 
    return b; 

}

輸出：

[Robert , Duchar 7345555555, Len , Gt 7345555567]

陣列寫入文件達特：將其寫入到輸出文件中之前陣列。

現在讓我們重新打開文件並顯示數組。

從輸入文件中讀入的數組... 您想查看數組的向後還是向前？輸入你的答案（B或F）：F

[null, null]

來源

2015-04-01 Robert Ducharme

您創建一個InputStream，但實際上並沒有讀什麼。 – DennisW 2015-04-01 05:53:09

您確實讀取了InputStream，但未保存在任何數組中。預計b [i] = input.Something – Sarz 2015-04-01 05:57:50

您聲明B，其中A null值初始化。

Datab[] b = null;

這樣，你就無處更新的b

值後來終於要返回b這是initialzed到null

來源

2015-04-01 05:56:24 niyasc

對象無法正常讀取

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