Question

我试图在ExpandableList内的TextView中显示设备的传感器列表，但是会发生此错误：

E / Android运行时：致命异常：主要流程：com.example.tpcubv4，PID：8045 java.lang.IllegalStateException：在onCreate（）之前，Activities无法使用系统服务在android.app.Activity.getSystemService（Activity.java:5998）在com.example.tpcubv4.control.DeviceSensors.sensorsList（DeviceSensors.java:21）在com.example.tpcubv4.MainActivity $ 1.onChildClick（MainActivity.java:45）在android.widget.ExpandableListView.handleItemClick（ExpandableListView.java:714）在android.widget.ExpandableListView.performItemClick（ExpandableListView.java:653）在android.widget.AbsListView $ PerformClick.run（AbsListView.java:4094）在android.widget.AbsListView $ 10.run（AbsListView.java:6583）在android.os.Handler.handleCallback（Handler.java:789）在android.os.Handler.dispatchMessage（Handler.java:98）在android.os.Looper.loop（Looper.java:164）在android.app.ActivityThread.main（ActivityThread.java:6944）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.Zygote $ MethodAndArgsCaller.run（Zygote.java:327）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1374）

但是我正在使用onCreate（）中的方法访问系统：

@Override
protected void onCreate(final Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    buildList();

    ExpandableListView expandableListView = findViewById(R.id.elv_expandable_list_view);
    expandableListView.setAdapter(new ExpandableAdapter(MainActivity.this, listGroup, listData));

    expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
        @Override
        public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
            if (listCurrentValue.equals(3)) {
                DeviceSensors deviceSensors = new DeviceSensors();
                deviceSensors.sensorsList();
                Toast.makeText(MainActivity.this, "Sensors List", Toast.LENGTH_SHORT).show();
            }
            return false;
        }
    });

    expandableListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
        @Override
        public void onGroupExpand(int groupPosition) {
            Toast.makeText(MainActivity.this, "List opened", Toast.LENGTH_SHORT).show();
        }
    });

    expandableListView.setOnGroupCollapseListener(new ExpandableListView.OnGroupCollapseListener() {
        @Override
        public void onGroupCollapse(int groupPosition) {
            Toast.makeText(MainActivity.this, "List closed", Toast.LENGTH_SHORT).show();
        }
    });

    expandableListView.setGroupIndicator(getResources().getDrawable(R.drawable.icon_group));

}

此方法在另一个类中：

public void sensorsList() {
    **sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);**
    List<Sensor> deviceSensors = sensorManager.getSensorList(Sensor.TYPE_ALL);
    TextView sensorsList = findViewById(R.id.tv_item);
    String value = new String("");
    sensorsList.setText(value);
    StringBuffer stringBuffer = new StringBuffer();
    for (int i = 0; i < deviceSensors.size(); i++) {
        sensorsList.setText(sensorsList.getText() + deviceSensors.get(i).getName() + "\n");
        stringBuffer.append(deviceSensors.get(i).getName() + "\n");
    }
    sensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    if (sensor != null)
        Toast.makeText(getApplicationContext(), "Detected the following sensors:\n" + stringBuffer, Toast.LENGTH_LONG);
    else
        Toast.makeText(getApplicationContext(), "There are no sensors", Toast.LENGTH_SHORT);
}

请注意，我的方法 onChildClick 位于 onCreate 方法

中

java.lang.IllegalStateException：在onCreate（）之前，活动无法使用系统服务，但是我已经做了

0 个答案: