android - ImageView 导致崩溃

Question

我对 Android 开发还很陌生，因此非常感谢任何帮助。

我有一个应用程序，它使用光传感器读取光量并将其显示在屏幕上。我正在android studio上开发它。标题下方是一个 textView，是一个 imageView，后面还有两个 TextView 。无论我尝试哪种布局，当我有 imageView 时，应用程序都会崩溃。一旦我删除 imageView，应用程序就会毫无问题地运行。我的图像位于可绘制包中(希望这是正确的术语)并且是 JPEG(根据文档，这是受支持的文件类型)。

此外，我了解到我的 textView 项目之一设置为等于“Light”，而不是指向字符串。我知道这不是我应该做的事情，我仍在开发该应用程序。

请帮我找出我做错了什么。我感谢所有的帮助和时间!

<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:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"
android:background="#ffffffff">

<TextView android:text="@string/title" android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textStyle="bold"
    android:textIsSelectable="false"
    android:textSize="@dimen/abc_text_size_headline_material"
    android:textColor="#ff2db81a"
    android:id="@+id/textView"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:id="@+id/light_available"
    android:text="Sensor"
    android:layout_marginBottom="35dp"
    android:layout_above="@+id/light_reading"
    android:layout_centerHorizontal="true" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:id="@+id/light_reading"
    android:text="Light"
    android:layout_marginBottom="43dp"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true" />

<ImageView
    android:layout_width="300dp"
    android:layout_height="300dp"
    android:id="@+id/imageView"
    android:layout_above="@+id/light_available"
    android:layout_centerInParent="true"
    android:layout_margin="10dp"
    android:src="@drawable/homeplant" />

这是 Java...

public class MainActivity extends ActionBarActivity {

TextView textLightIsAvailable, textLightReading;

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

    textLightIsAvailable = (TextView)findViewById(R.id.light_available);
    textLightReading  = (TextView)findViewById(R.id.light_reading);

    SensorManager mySensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);

    Sensor LightSensor = mySensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
    if(LightSensor != null){
        textLightIsAvailable.setText("You Have a Sensor!");
        mySensorManager.registerListener(LightSensorListener, LightSensor, SensorManager.SENSOR_DELAY_NORMAL);

    }
    else{
        textLightIsAvailable.setText("You Don't Have a Sensor!");
    }
}

private final SensorEventListener LightSensorListener= new SensorEventListener(){

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        if(event.sensor.getType() == Sensor.TYPE_LIGHT){
            textLightReading.setText("LIGHT: " + event.values[0]);
        }
    }

};

更新:2015 年 3 月 10 日:我也尝试了两种不同的虚拟设备，但出现与物理设备相同的错误。 logcat 仅显示(我取出了时间戳/我的包名称，因为它在此处的格式看起来如何)...

I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ waiting for debugger to settle...
I/System.out﹕ debugger has settled (1433)

再次感谢。

编辑:2015 年 3 月 12 日

我的 JRE 版本是 - 1.6.0_65-B14-466.1 11M4716 x86_64Android Studio 版本 - 1.1.0

Answer 1

我认为你必须写

android:layout_above="@id/light_available"

而不是

android:layout_above="@+id/light_available"

我不知道如何使用layout_above，但是看到@+id两次很奇怪。

编辑 1:正如我在评论中所说

• @id/someId 引用项目中现有的 ID
• @+id/someId 在您的项目中创建一个新 ID

我认为你必须将代码更改为

<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:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"
android:background="#ffffffff">

<TextView android:text="@string/title" android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textStyle="bold"
    android:textIsSelectable="false"
    android:textSize="@dimen/abc_text_size_headline_material"
    android:textColor="#ff2db81a"
    android:id="@+id/textView"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:id="@+id/light_available"
    android:text="Sensor"
    android:layout_marginBottom="35dp"
    android:layout_above="@id/light_reading"
    android:layout_centerHorizontal="true" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:id="@+id/light_reading"
    android:text="Light"
    android:layout_marginBottom="43dp"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true" />

<ImageView
    android:layout_width="300dp"
    android:layout_height="300dp"
    android:id="@+id/imageView"
    android:layout_above="@id/light_available"
    android:layout_centerInParent="true"
    android:layout_margin="10dp"
    android:src="@drawable/homeplant" />

如果这个答案不起作用，here是一个有替代想法的线程。 (您会注意到 @id 与 android:layout_above 的使用)

编辑2:这是一个新代码(我测试了这个代码，它对我有用)。

Under the title, which is a textView, is an imageView, followed by two more text views.

<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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"
    android:background="#ffffffff">

    <TextView
        android:id="@+id/textView"
        android:text="@string/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:textIsSelectable="false"
        android:textSize="@dimen/abc_text_size_headline_material"
        android:textColor="#ff2db81a"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_below="@id/textView"
        android:layout_margin="10dp"
        android:src="@drawable/homeplant" />

    <TextView
        android:id="@+id/light_available"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Sensor"
        android:layout_below="@id/imageView"
        android:layout_marginBottom="35dp"
        android:layout_centerHorizontal="true" />

    <TextView
        android:id="@+id/light_reading"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Light"
        android:layout_marginBottom="43dp"
        android:layout_alignParentBottom="true"
        android:layout_below="@id/light_available"
        android:layout_centerHorizontal="true" />

</RelativeLayout>

按照您想要的显示顺序放置元素会更容易。在这种情况下，您还可以使用 LinearLayout。这是代码

<LinearLayout
    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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"
    android:background="#ffffffff"
    android:orientation="vertical">

    <TextView
        android:id="@+id/textView"
        android:text="@string/title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:textIsSelectable="false"
        android:textSize="@dimen/abc_text_size_headline_material"
        android:textColor="#ff2db81a"
        android:gravity="center"/>

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_below="@id/textView"
        android:layout_margin="10dp"
        android:src="@drawable/homeplant"
        android:layout_gravity="center"/>

    <TextView
        android:id="@+id/light_available"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Sensor"
        android:layout_below="@id/imageView"
        android:layout_marginBottom="35dp"
        android:gravity="center" />

    <TextView
        android:id="@+id/light_reading"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Light"
        android:layout_marginBottom="43dp"
        android:layout_alignParentBottom="true"
        android:layout_below="@id/light_available"
        android:layout_centerHorizontal="true"
        android:gravity="center"/>

</LinearLayout>

编辑3:

public class MainActivity extends ActionBarActivity implements SensorEventListener {

    TextView textLightIsAvailable, textLightReading;

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

        textLightIsAvailable = (TextView) findViewById(R.id.light_available);
        textLightReading = (TextView) findViewById(R.id.light_reading);

        SensorManager mySensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

        Sensor lightSensor = mySensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
        if (lightSensor != null) {
            textLightIsAvailable.setText("You Have a Sensor!");
            mySensorManager.registerListener(this, lightSensor, SensorManager.SENSOR_DELAY_NORMAL);
        } else {
            textLightIsAvailable.setText("You Don't Have a Sensor!");
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // TODO Auto-generated method stub
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        if (event.sensor.getType() == Sensor.TYPE_LIGHT) {
            textLightReading.setText("LIGHT: " + event.values[0]);
        }
    }
}