Parcelable類

Question

我有一個類下面，並希望實施Parcelable。 我遇到了錯誤。請指教。

in.readValue(row); 

錯誤消息：該方法readValue（類加載器）在類型包裹不適用的參數（ArrayList的）

import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.Hashtable; 
import java.util.Iterator; 

import android.os.Parcel; 
import android.os.Parcelable; 

public class cls_datatable implements Parcelable { 
private ArrayList<String> column = new ArrayList<String>(); 
private ArrayList<cls_datarow> row = new ArrayList<cls_datarow>(); 
private int indexCounter = 0; 
private Hashtable<Integer, Integer> IDnIndex = new Hashtable<Integer, Integer>(); 

public cls_datatable(Parcel in) { 
    readFromParcel(in); 
} 

public class cls_datarow { 

    private ArrayList<String> columnValues; 
    private int id; 

    public cls_datarow(int id) { 
     this.id = id; 
     columnValues = new ArrayList<String>(); 
     for (int i = 0; i < column.size(); i++) 
      columnValues.add(null); 
    } 

    public cls_datarow() { 
     columnValues = new ArrayList<String>(); 
     for (int i = 0; i < column.size(); i++) 
      columnValues.add(null); 
    } 

    public int getID() { 
     return id; 
    } 

    public String get(String columnName) { 
     return columnValues.get(column.indexOf(columnName)); 
    } 

    public String get(int columnIndex) { 
     return columnValues.get(columnIndex); 
    } 

    public void set(String columnName, String value) { 
     columnValues.set(column.indexOf(columnName), value); 
    } 

    public void set(int columnIndex, String value) { 
     columnValues.set(columnIndex, value); 
    } 

    public int getColumnSize() { 
     return column.size(); 
    } 
} 

public void addColumn(String columnName) { 
    column.add(columnName); 
} 

// Depreciated function 
public void addAllColumns(ArrayList<String> columns) { 
    column.addAll(columns); 
} 

public void addAllColumns(String[] columns) { 
    for (String col : columns) { 
     column.add(col); 
    } 
} 

public int getColumnSize() { 
    return column.size(); 
} 

public int getColumnIndex(String columnName) { 
    return column.indexOf(columnName); 
} 

public int getRowSize() { 
    return row.size(); 
} 

public cls_datarow getRow(int rowIndex) { 
    return row.get(rowIndex); 
} 

public void remove(int rowIndex) { 
    row.remove(rowIndex); 
    refreshIDnIndex(); 
} 

public void remove(cls_datarow dataRow) { 
    row.remove((int) IDnIndex.get(dataRow.getID())); 
    refreshIDnIndex(); 
} 

public void update(cls_datarow dataRow) { 
    row.set(IDnIndex.get(dataRow.getID()), dataRow); 
} 

public void add(cls_datarow row) { 
    IDnIndex.put(row.getID(), this.row.size()); 
    this.row.add(row); 
} 

public void addAllRows(ArrayList<cls_datarow> row) { 
    for (cls_datarow r : row) { 
     IDnIndex.put(r.getID(), this.row.size()); 
     this.row.add(r); 
    } 
} 

public cls_datarow newRow() { 
    cls_datarow dr = new cls_datarow(indexCounter); 
    indexCounter++; 
    return dr; 
} 

public cls_datatable copy() { 
    cls_datatable dt = new cls_datatable(null); 
    dt.addAllColumns(column); 
    dt.addAllRows(row); 
    return dt; 
} 

// inappropriate method 
public ArrayList<cls_datarow> getAllRows() { 
    return row; 
} 

public void clear() { 
    row.clear(); 
} 

public cls_datarow[] select(HashMap<String, String> condition) { 
    ArrayList<cls_datarow> rs = new ArrayList<cls_datarow>(); 
    boolean isMatch = true; 
    Iterator<String> i; 

    for (cls_datarow r : row) { 
     isMatch = true; 
     i = condition.keySet().iterator(); 
     while (i.hasNext()) { 
      String key = i.next(); 
      if (r.get(key) == null && condition.get(key) != null) 
       isMatch = false; 
      if (r.get(key) != null && condition.get(key) == null) 
       isMatch = false; 
      if (r.get(key) != null && condition.get(key) != null 
        && !r.get(key).equals(condition.get(key))) 
       isMatch = false; 
     } 

     if (isMatch) 
      rs.add(r); 
    } 

    return rs.toArray(new cls_datarow[rs.size()]); 
} 

private void refreshIDnIndex() { 
    IDnIndex.clear(); 
    for (int i = 0; i < row.size(); i++) 
     IDnIndex.put(row.get(i).getID(), i); 
} 

@Override 
public int describeContents() { 
    // TODO Auto-generated method stub 
    return 0; 
} 


@Override 
public void writeToParcel(Parcel dest, int flags) { 

    // We just need to write each field into the 
    // parcel. When we read from parcel, they 
    // will come back in the same order 
    dest.writeStringList(column); 
    dest.writeValue(row); 
    dest.writeInt(indexCounter); 
    dest.writeValue(IDnIndex); 
} 

private void readFromParcel(Parcel in) { 

    // We just need to read back each 
    // field in the order that it was 
    // written to the parcel 
    in.readStringList(column); 
    in.readValue(row); 
    //indexCounter 
    //IDnIndex 
} 


public static final Parcelable.Creator CREATOR = 
    new Parcelable.Creator() { 
     public cls_datatable createFromParcel(Parcel in) { 
      return new cls_datatable(in); 
     } 

     public cls_datatable[] newArray(int size) { 
      return new cls_datatable[size]; 
     } 
    }; 

}

Answer 1

該錯誤是因爲readValue期待一個對象ClassLoader，你傳遞給它一個ArrayList。但是，更大的問題是，你不能僅僅打包和不打印任何類型的對象列表。看看在writeValue的文檔：需求

http://developer.android.com/reference/android/os/Parcel.html#writeValue(java.lang.Object）

你的類cls_datarow通過這種方法以某種方式予以支持。我只需要cls_datarow執行Paracable並使用writeTypedList來編寫它，然後createTypedArrayList來讀取它。