手柄屏幕旋转而不会丢失数据 - 机器人 [英] Handle screen rotation without losing data - Android

问题描述

我变得疯狂搞清楚什么是处理屏幕旋转的最佳方式。我看了几百个问题在这里/答案，但我真的很困惑。

我如何保存MyClass的数据重新创建活动之前，这样我就可以把一切都重新绘制活动，无须另外一个无用的初始化？

有没有比parcelable一个更清洁，更好的办法？

我需要处理的旋转，因为我想改变布局横向模式。

 公共类MtgoLifecounterActivity延伸活动{

    MyClass的MyClass的;

    //第一次创建活动时调用
    @覆盖
    公共无效的onCreate（包savedInstanceState）{
        super.onCreate（savedInstanceState）;
        的setContentView（R.layout.main）;

        如果（??第一次运行... MyClass的== NULL？）{
            MyClass的=新MyClass的（）;
        } 其他 {
            //做其他的东西，但我需要MyClass的istance所有值。
        }
        //我想，这是所谓的只有第一次。
        //则在发生屏幕的旋转，我想要恢复myClass的其他实例，
        //充满数据。
    }
 

解决方案

可以使用覆盖方法的onSaveInstanceState（）和 onRestoreInstanceState（）。 或停止呼叫的onCreate（）在屏幕旋转刚加入这一行你的清单XML 安卓configChanges =keyboardHidden |定位

请注意：您的自定义类必须农具 Parcelable 下面的例子

  @覆盖
    公共无效的onSaveInstanceState（包outState）{
        super.onSaveInstanceState（outState）;
        outState.putParcelable（目标文件，MyClass的）;
    }

@覆盖
保护无效onRestoreInstanceState（包savedInstanceState）{
 // TODO自动生成方法存根
 super.onRestoreInstanceState（savedInstanceState）;
 MyClass的= savedInstanceState.getParcelable（目标文件））;
}

公共类MyClass的实现Parcelable {
     私人诠释MDATA;

 公众诠释describeContents（）{
     返回0;
 }

 / **保存对象包裹* /
 公共无效writeToParcel（包裹出来，诠释标志）{
     out.writeInt（MDATA）;
 }

 公共静态最终Parcelable.Creator＆LT; MyParcelable＆GT; CREATOR
         =新Parcelable.Creator＆LT; MyParcelable＆GT;（）{
     公共MyParcelable createFromParcel（包裹中）{
         返回新MyParcelable（中）;
     }

     公共MyParcelable [] newArray（INT尺寸）{
         返回新MyParcelable【尺寸】;
     }
 };

 / **从包裹*重建对象/
 私人MyParcelable（包裹中）{
     MDATA = in.readInt（）;
 }


}
 

I'm becoming crazy figuring out what is the best way to handle screen rotation. I read hundreds of questions/answers here but I'm really confused.

How can I save myClass data before the activity is re-created so I can keep everything for redrawing activity without another useless initialization?

Is there a cleaner and better way than parcelable?

I need to handle rotation because I want to change layout in Landscape mode.

public class MtgoLifecounterActivity extends Activity {

    MyClass myClass;

    // Called when the activity is first created
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        If ( ?? first run...myClass == null ? ) {
            myClass = new MyClass();
        } else {
            // do other stuff but I need myClass istance with all values.
        }
        // I want that this is called only first time. 
        // then in case of rotation of screen, i want to restore the other instance of myClass which
        // is full of data.
    }

解决方案

can use override method onSaveInstanceState() and onRestoreInstanceState(). or to stop calling onCreate() on screen rotation just add this line in your manifest xml android:configChanges="keyboardHidden|orientation"

note: your custom class must implements Parcelable example below.

@Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putParcelable("obj", myClass);
    }

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
 // TODO Auto-generated method stub
 super.onRestoreInstanceState(savedInstanceState);
 myClass=savedInstanceState.getParcelable("obj"));
}

public class MyClass implements Parcelable {
     private int mData;

 public int describeContents() {
     return 0;
 }

 /** save object in parcel */
 public void writeToParcel(Parcel out, int flags) {
     out.writeInt(mData);
 }

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

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

 /** recreate object from parcel */
 private MyParcelable(Parcel in) {
     mData = in.readInt();
 }


}

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