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我对 Android 编程相对较新，我被困在一个（可能很简单）问题上。我已经尝试了几个小时的胡闹，但一无所获......

我的代码如下，当设备旋转并重新启动活动时，它会停止应用程序。我使用了 onSaveInstanceState 和 onRestoreInstanceState 方法，但它们对我没有帮助！有人可以看看吗：

public class DebugActivity extends Activity implements GPSCallback{
private GPSManager gpsM=null;
private ConvertSpeed conS =null;
private double speed = 0.0;

    @Override
    public void onCreate(Bundle savedInstanceState){
        if(savedInstanceState != null){
            speed = savedInstanceState.getDouble("speed");
        }

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_debug);
        gpsM = new GPSManager();
        gpsM.startListening(getApplicationContext());
        gpsM.setGPSCallback(this);
        conS = new ConvertSpeed();
    }
    @Override
    public void onSaveInstanceState(Bundle outState){
        outState.putDouble("speed",speed);
        super.onSaveInstanceState(outState);
    }
    @Override
    public void onRestoreInstanceState(Bundle savedInstanceState){
        super.onRestoreInstanceState(savedInstanceState);
        speed = savedInstanceState.getDouble("speed");
    }
@Override
    public void onDestroy(){
        gpsM.stopListening();
        gpsM.setGPSCallback(null);
        gpsM = null;
    }
    @Override
    public void onGPSUpdate(Location location) {
        location.getLatitude();
        location.getLongitude();
        speed = location.getSpeed();
        String speedString = "" + conS.convertSpeed(speed,2);
        TextView debug1 = ((TextView)findViewById(R.id.tvSpeed));
        debug1.setText(speedString);
    }
}

调试：

方法中onCreate，Activity第一次运行：

if(savedInstanceState != null){
speed = savedInstanceState.getDouble("speed");

它显示outState = null和speed = 0.0

屏幕旋转，onSaveInstanceState方法显示outState = Bundle[{speed=0.0}]，然后2秒后它没有到达onRestoreInstanceState或onCreate再次崩溃

4

2 回答 2

0

将其替换onCreate为

@Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_debug);

        if(savedInstanceState != null){
            speed = savedInstanceState.getDouble("speed");
        }

        gpsM = new GPSManager();
        gpsM.startListening(getApplicationContext());
        gpsM.setGPSCallback(this);
        conS = new ConvertSpeed();
    }

并onSaveInstanceState_

 @Override
    public void onSaveInstanceState(Bundle outState){
        super.onSaveInstanceState(outState);
        outState.putDouble("speed",speed);
    }

删除这个onRestoreInstanceState

 @Override
    public void onRestoreInstanceState(Bundle savedInstanceState){
        super.onRestoreInstanceState(savedInstanceState);
        speed = savedInstanceState.getDouble("speed");
    }

在你这样做之后，它应该可以正常工作

于 2013-11-01T23:11:23.983 回答
0

我更深入地查看了调试日志（在 3075 次谷歌搜索之后......），错误似乎是我没有打电话super.onDestroy()！它现在似乎工作！

于 2013-11-04T16:10:58.003 回答