1

问题如下 - 我开始活动，当我想拍摄图像时，我用 startActivityForResult(intent) 调用相机（按钮 onclick），位图的意图正常返回，我将位图分配给 CounterUser 对象中的属性（它的类实现了 parcelable）并最后在 ImageView 上显示它 - 这工作正常..但是为了处理方向更改，我在活动中添加了以下代码 - 这会导致 NullPointerException 并关闭活动：

注意 - counterObj 是我实现 Parcelable 接口的 CounterUser 类的实例。

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);

    outState.putParcelable("counterObj", counterObj);
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);

    if(savedInstanceState != null){
    counterObj = savedInstanceState.getParcelable("counterObj");
    counterImgView.setImageBitmap(counterObj.counterImg);
    }   
}

错误：

在此处输入图像描述

这是我实现 Parcelable 接口的类 - 它还有一个 Bitmap 属性......它使用两个构造函数 - 在活动中，我使用第一个无参数构造函数将空值分配给所有实例属性

public class CounterUser implements Parcelable {


String fname;
String lname;
String adresse;
Integer counterID;
Integer counterValue;
Bitmap counterImg;
Boolean damageExists;
String damageDescript;
//----
Double longitude;
Double latitude;
Integer workerID;
String updateDate;


public CounterUser(){

    this(null,null,null,null,null,null,null,null,null,null,null,null);  
}

public CounterUser(String fname, String lname, String adresse, Integer counterID, Integer counterValue, Bitmap counterImg, Boolean damageExists, 
        String damageDescript, Double longitude, Double latitude, Integer workerID, String updateDate){

    this.fname = fname;
    this.lname = lname;
    this.adresse = adresse;
    this.counterID = counterID;
    this.counterValue = counterValue;
    this.counterImg = counterImg;
    this.damageExists = damageExists;
    this.damageDescript = damageDescript;
    this.longitude = longitude;
    this.latitude = latitude;
    this.workerID = workerID;
    this.updateDate = updateDate;

}

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

@Override
public void writeToParcel(Parcel dest, int flags) {
    dest.writeString(this.fname);
    dest.writeString(this.lname);
    dest.writeString(this.adresse);
    dest.writeInt(this.counterID);
    dest.writeInt(this.counterValue);
    //Bitmap je parcelable
    this.counterImg.writeToParcel(dest, flags);

    dest.writeByte((byte) (this.damageExists ? 1 : 0)); 
    dest.writeString(this.damageDescript);
    dest.writeDouble(this.longitude);
    dest.writeDouble(this.latitude);
    dest.writeInt(this.workerID);
    dest.writeString(this.updateDate);

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

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

    private CounterUser(Parcel in) {

        this.fname = in.readString();
        this.lname = in.readString();
        this.adresse = in.readString();
        this.counterID = in.readInt();
        this.counterValue = in.readInt();
        //Bitmap je parcelable
        this.counterImg = Bitmap.CREATOR.createFromParcel(in);

        this.damageExists = in.readByte() == 1;
        this.damageDescript = in.readString();
        this.longitude = in.readDouble();
        this.latitude = in.readDouble();
        this.workerID = in.readInt();
        this.updateDate = in.readString();
    }

}

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1 回答 1

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你如何创建 CounterUser 实例？如果你使用空的公共构造函数，你有很多空成员字段会导致writeToParcel抛出 NPE。您要么不允许空字段，要么在保存实例时处理它们。

于 2013-04-26T17:35:11.760 回答