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我正在尝试在片段中使用计步器传感器来计算自设备上次重新启动以来已采取的步数。

我可以让计步器在 中工作，Activity但似乎无法在fragment. 我是使用片段的新手，所以我做错的事情可能很简单。

我的课如下：

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import static com.example.application.placepicker.R.id.count;


public class Tab3 extends Fragment implements SensorEventListener {

private SensorManager sensorManager;
private TextView textView;
boolean activityRunning;
private Button buttonReturn;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.tab3, container, false);
    return rootView;
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    count = (TextView) getActivity().findViewById(count);  **error

    sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);     **error

}

@Override
public void onResume() {
    super.onResume();
    activityRunning = true;
    Sensor countSensor = sensorManager.getDefaultSensor(Sensor.TYPE_STEP_COUNTER);
    if (countSensor != null) {
        sensorManager.registerListener(this, countSensor, SensorManager.SENSOR_DELAY_UI);
    } else {
        Toast.makeText(this, "Count sensor not available!", Toast.LENGTH_LONG).show();                            **error
    }

}

@Override
public void onPause() {
    super.onPause();
    activityRunning = false;
}

@Override
public void onSensorChanged(SensorEvent event) {
    if (activityRunning) {
        count.setText(String.valueOf(event.values[0]));         **error
    }

}

@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {

}
}

我的 XML 文件是：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.application.placepicker.TabbedActivity$PlaceholderFragment">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:layout_marginTop="114dp"
    android:gravity="center"
    android:layout_alignParentTop="true"
    android:layout_alignParentStart="true">

    <TextView
        android:id="@+id/textLogin"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="Step counter"
        android:textSize="40sp"
        android:textColor="@color/colorAccent"
        android:fontFamily="sans-serif"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="33dp"
        android:layout_gravity="center_horizontal"
        android:textSize="26dp"
        android:text="Steps walked so far today:"
        android:textColor="@color/colorAccent" />

    <TextView
        android:id="@+id/count"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="40dp"
        android:layout_marginLeft="50dp"
        android:text="---"
        android:textColor="@color/colorAccent"
        android:textSize="36dp" />

</LinearLayout>

4

2 回答 2

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您没有 count 的成员变量

private SensorManager sensorManager;
private TextView textView;
boolean activityRunning;
private Button buttonReturn;

是片段类中成员变量的示例

count = (TextView) getActivity().findViewById(count);

正在将 TextView 设置为未知引用，请正确初始化计数，即

TextView count = (TextView) getActivity().findViewById(count);

作为函数成员或：

private TextView count;

与其他类成员变量

然后你需要打电话

sensorManager = (SensorManager) getActivity().getSystemService(Context.SENSOR_SERVICE)

由于片段本身没有引用 getSystemService 方法，所以它需要通过它的持有活动

于 2017-12-06T00:29:11.310 回答
0

我也知道你应该改变

 count = (TextView) getActivity().findViewById(count);

至

count = (TextView)getView().findViewById(R.id.count);

因为你必须定义 view ，不要调用活动。

于 2021-07-17T17:10:18.177 回答