android - 尝试在自定义对象数组上使用 ParcelableArrayList 时发生 ClassCastException

Question

我正在尝试实现 Parcelable而不是 Serializable因为它应该更有效率。

来 self 的 MainActivity我想传递通用类型的对象 ArrayList<LogChartData>到相同的 Activity ，以便我在方向改变时得到它。

如果我克服了这个错误，我肯定会遇到更多错误，但现在当我尝试运行我的应用程序时，我得到了，

Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.util.Date
at com.testapp.util.LogChartData.<init>(LogChartData.java:60)
at com.testapp.util.LogChartData.<init>(LogChartData.java:59)
at com.testapp.util.LogChartData$1.createFromParcel(LogChartData.java:51)
at com.testapp.util.LogChartData$1.createFromParcel(LogChartData.java:1)
at android.os.Parcel.readParcelable(Parcel.java:2103)
at android.os.Parcel.readValue(Parcel.java:1965)

MainActivity.java--

    ArrayList<LogChartData> logss = new ArrayList<LogChartData>();

@Override
    public void onSaveInstanceState(final Bundle outState) {
        outState.putParcelableArrayList("logss", logss);
        outState.putParcelableArrayList("alert", alert);
        outState.putBoolean("isRotate", true);
        super.onSaveInstanceState(outState);
    }


  @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        super.onCreateView(inflater, container, savedInstanceState);

        if (savedInstanceState != null) {

            try
            {
                logss = savedInstanceState.getParcelableArrayList("logss");
                alert = savedInstanceState.getParcelableArrayList("alert");
                isRotate = savedInstanceState.getBoolean("isRotate");
            }
            catch(ClassCastException e)
            {
                e.printStackTrace();
            }

            if(!isRotate)
              someFunctionCall();

                    // More code here..
        }
}

LogCharData.java --

public class LogChartData implements Parcelable {

    public Date chartDate = null;
    public ArrayList<LogEntries> logs = new ArrayList<LogEntries>();

    public LogChartData(Date chartDate, ArrayList<LogEntries> logs) {
        super();
        this.chartDate = chartDate;
        this.logs = logs;
    }

    public LogChartData() {
    }

    @Override
    public int describeContents() {
        return 0;
    }

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

    }

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

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

    private LogChartData(Parcel in) {
        this.chartDate = 
    (Date)in.readValue(LogChartData.class.getClassLoader()); //Error Here..
        in.readList(logs, LogChartData.class.getClassLoader());

    }

    public Date getChartDate() {
        return chartDate;
    }

    public void setChartDate(Date chartDate) {
        this.chartDate = chartDate;
    }

    public ArrayList<LogEntries> getLogs() {
        return logs;
    }

    public void setLogs(ArrayList<LogEntries> logs) {
        this.logs = logs;
    }
}

Answer 1

您不能像这样直接将字符串变量直接转换为 Date 对象

(Date)in.readValue(LogChartData.class.getClassLoader());

需要使用SimpleDateFormat，从指定的DateFormat中解析出String，然后存储到Date对象中

假设你的日期格式为"yyyy-MM-dd"

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

this.chartDate= format.parse(in.readValue(LogChartData.class.getClassLoader()));