EF为Navagation属性返回null（ef添加数据返回id）

25-02-25 13

关于EF为Navagation属性返回null和ef添加数据返回id的问题就给大家分享到这里，感谢你花时间阅读本站内容，更多关于AndroidMediaProjectionacquisitionLat

关于EF为Navagation属性返回null和ef添加数据返回id的问题就给大家分享到这里，感谢你花时间阅读本站内容，更多关于Android MediaProjection acquisitionLatestImage始终为ImageReader返回Null、android – IllegalArgumentException：savedInstanceState指定为Non-Null为Null、android – IllegalStateException：NavigationDrawer活动中的Fragment内的RecyclerView为null、Application.Current返回null等相关知识的信息别忘了在本站进行查找喔。

本文目录一览：

EF为Navagation属性返回null（ef添加数据返回id）
Android MediaProjection acquisitionLatestImage始终为ImageReader返回Null
android – IllegalArgumentException：savedInstanceState指定为Non-Null为Null
android – IllegalStateException：NavigationDrawer活动中的Fragment内的RecyclerView为null
Application.Current返回null

EF为Navagation属性返回null（ef添加数据返回id）

从上述ModelBuilder配置中，我们可以看到您错误地将Item.Id用作ForeignKey来绑定课程。
您应该像下面的代码一样将public int CourseRef { get; set; }设置为ForeignKey。

在实体框架核心中配置一对一关系

public class Course
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public ICollection<CategoryToCourse> Categories { get; set; }
    public ICollection<AuthorToCourse> Authors { get; set; }
    public Item Item { get; set; }
}
public class Item 
{
    public int Id { get; set; }
    public decimal Price { get; set; }
    public int CourseRef { get; set; }
    public Course Course { get; set; }
}


modelBuilder.Entity<Course>()
    .HasOne(a => a.Item)
    .WithOne(b => b.Course)
    .HasForeignKey<Item>(i => i.CourseRef);

Android MediaProjection acquisitionLatestImage始终为ImageReader返回Null

如何解决Android MediaProjection acquisitionLatestImage始终为ImageReader返回Null？

我正在编写简单的Screenshot应用程序，并为此使用MediaProjection + ImageReader。我使用some sample解决此任务。
当我单击“捕获”按钮时，我总是在日志消息中得到"image: NULL"。

在ImageReader.newInstance中，我将格式设置为ImageFormat.RGB_565。默认值为0x1，但是当我使用此值时，会显示警告消息：

必须是以下之一：ImageFormat.UNKNowN，ImageFormat.RGB_565， ImageFormat.YV12，ImageFormat.Y8，ImageFormat.NV16，ImageFormat.NV21， ImageFormat.YUY2，ImageFormat.JPEG，ImageFormat.DEPTH_JPEG， ImageFormat.YUV_420_888，ImageFormat.YUV_422_888， ImageFormat.YUV_444_888，ImageFormat.FLEX_RGB_888， ImageFormat.FLEX_RGBA_8888，ImageFormat.RAW_SENSOR， ImageFormat.RAW_PRIVATE，ImageFormat.RAW10，ImageFormat.RAW12， ImageFormat.DEPTH16，ImageFormat.DEPTH_POINT_CLOUD， ImageFormat.PRIVATE，ImageFormat.HEIC

我的问题：为什么 ImageReader 中的 Image 总是 Null ？以及如何正确解决？谢谢

我的代码：

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.ImageFormat;
import android.hardware.display.displayManager;
import android.hardware.display.Virtualdisplay;
import android.media.Image;
import android.media.ImageReader;
import android.media.projection.MediaProjection;
import android.media.projection.mediaprojectionmanager;
import android.os.Bundle;
import android.os.Environment;
import android.util.displayMetrics;
import android.util.Log;
import android.view.View;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private static final String TAG = "test_t";

    private ImageReader mImageReader;
    private mediaprojectionmanager mmediaprojectionmanager;
    private Intent mCreateScreenCaptureIntent;
    private MediaProjection mMediaProjection;
    private Virtualdisplay mVirtualdisplay;

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

        View mBtnCapture = findViewById(R.id.btn_capture);
        mBtnCapture.setonClickListener(this);

        init();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        tearDownMediaProjection();
    }

    @Override
    protected void onActivityResult(int requestCode,int resultCode,Intent data) {
        super.onActivityResult(requestCode,resultCode,data);
        mMediaProjection = mmediaprojectionmanager.getMediaProjection(resultCode,data);
        if (mMediaProjection != null) {
            startScreenCapture();
            takeCapture();
            stopScreenCapture();
        }
    }

    @Override
    public void onClick(View v) {
        startActivityForResult(mCreateScreenCaptureIntent,777);
    }

    private void init() {
        displayMetrics displayMetrics = getResources().getdisplayMetrics();
        mImageReader = ImageReader.newInstance(displayMetrics.widthPixels,displayMetrics.heightPixels,ImageFormat.RGB_565,2); // format 0x1

        mmediaprojectionmanager = (mediaprojectionmanager) getSystemService(MEDIA_PROJECTION_SERVICE);
        mCreateScreenCaptureIntent = mmediaprojectionmanager.createScreenCaptureIntent();
    }

    private void startScreenCapture() {
        if (mMediaProjection == null)
            return;

        displayMetrics displayMetrics = getResources().getdisplayMetrics();
        mVirtualdisplay = mMediaProjection.createVirtualdisplay(
                "ScreenCapture",displayMetrics.widthPixels,displayMetrics.densityDpi,displayManager.VIRTUAL_disPLAY_FLAG_AUTO_MIRROR,mImageReader.getSurface(),null,null);
    }

    private void stopScreenCapture() {
        if (mVirtualdisplay == null) {
            return;
        }
        mVirtualdisplay.release();
        mVirtualdisplay = null;
    }

    private void takeCapture() {
        Image image = mImageReader.acquireLatestimage();
        if (image == null) {
            Log.d(TAG,"image: NULL");
            return;
        }

        int width = image.getWidth();
        int height = image.getHeight();
        final Image.Plane[] planes = image.getPlanes();
        final ByteBuffer buffer = planes[0].getBuffer();
        int pixelStride = planes[0].getPixelStride();
        int rowStride = planes[0].getRowStride();
        int rowPadding = rowStride - pixelStride * width;
        Bitmap mBitmap = Bitmap.createBitmap(width + rowPadding / pixelStride,height,Bitmap.Config.ARGB_8888);
        mBitmap.copyPixelsFromBuffer(buffer);
        mBitmap = Bitmap.createBitmap(mBitmap,width,height);
        image.close();
        saveBitmapToFile(mBitmap);
    }

    private void saveBitmapToFile(Bitmap bitmap) {
        File directory = new File(Environment.getExternalStorageDirectory(),"SCREEN_TEMP");
        if (!directory.exists())
            directory.mkdirs();
        String name = "shot" + new SimpleDateFormat("yyyyMMddHHmmsss").format(new Date()) + "." + Bitmap.CompressFormat.PNG.toString();
        File file = new File(directory,name);
        try {
            if (!file.exists()) {
                file.createNewFile();
            }
            FileOutputStream out = new FileOutputStream(file);
            bitmap.compress(Bitmap.CompressFormat.PNG,100,out);
            out.flush();
            out.close();
        } catch (IOException e) {
            e.printstacktrace();
        }
    }

    private void tearDownMediaProjection() {
        if (mMediaProjection != null) {
            mMediaProjection.stop();
            mMediaProjection = null;
        }
    }
}

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

如果你已经找到好的解决方法，欢迎将解决方案带上本链接一起发送给小编。

小编邮箱:dio#foxmail.com (将#修改为@）

android – IllegalArgumentException：savedInstanceState指定为Non-Null为Null

当我启动MainActivity时出现一个奇怪的错误：

06-16 16:01:05.193 2083-2083/? E/AndroidRuntime: FATAL EXCEPTION: main
        Process: com.android.example.github, PID: 2083
        java.lang.RuntimeException: Unable to start activity ComponentInfo{com.android.example.github/com.android.example.github.ui.MainActivity}: java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter savedInstanceState
            at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2666)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2727)
            at android.app.ActivityThread.-wrap12(ActivityThread.java)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1478)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:154)
            at android.app.ActivityThread.main(ActivityThread.java:6121)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)
          Caused by: java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter savedInstanceState
            at com.android.example.github.injection.AppInjector$init$1.onActivityCreated(AppInjector.kt)
            at android.app.Application.dispatchActivityCreated(Application.java:197)
            at android.app.Activity.onCreate(Activity.java:961)
            at android.support.v4.app.BaseFragmentActivityGingerbread.onCreate(BaseFragmentActivityGingerbread.java:54)
            at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:319)
            at com.android.example.github.ui.MainActivity.onCreate(MainActivity.kt:20)
            at android.app.Activity.performCreate(Activity.java:6682)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
            at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2619)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2727) 
            at android.app.ActivityThread.-wrap12(ActivityThread.java) 
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1478) 
            at android.os.Handler.dispatchMessage(Handler.java:102) 
            at android.os.Looper.loop(Looper.java:154) 
            at android.app.ActivityThread.main(ActivityThread.java:6121) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)

这是我的MainActivity类：

class MainActivity : LifecycleActivity(), HasSupportFragmentInjector {

    lateinit var dispatchingAndroidInjector: dispatchingAndroidInjector<Fragment>
        @Inject set

    lateinit var navigationController: NavigationController

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.main_activity)

        if (savedInstanceState == null) {
            navigationController.navigatetoSearch()
        }
    }

    override fun supportFragmentInjector(): AndroidInjector<Fragment> {
        return dispatchingAndroidInjector
    }

}

该错误表明参数savedInstanceState为null,当它被指定为非null时;但它可以为空(savedInstanceState：Bundle？),并且onCreate()方法在源中标记为@Nullable.

我在任何其他Kotlin项目中都没有遇到过这个错误.我正在使用Kotlin版本1.1.2-5;与1.1.2-3有同样的错误.

解决方法:

似乎问题不在onCreate方法中.尝试查看com.android.example.github.injection.AppInjector $init $1.onActivityCreated(AppInjector.kt).我不知道它是否是一个生成的类,但它应该让你知道下一步该做什么.

android – IllegalStateException：NavigationDrawer活动中的Fragment内的RecyclerView为null

我试图制作一个RecyclerView,它将进入我片段的两个页面之一.这些页面放在NavigationDrawer活动中.目标是创建类似Play商店应用主页的内容.

但是我在运行时的代码片段中发现了一个错误.它说：

java.lang.IllegalStateException: mainMenu must not be null
    at com.example.MyApp.app.fragment.MainFragment.onCreate(MainFragment.kt:49)

我一直在看一些SO线程,他们说布局没有正确加载.这导致一些元素没有被链接起来.另一位在评论中说,问题在于上下文未正确初始化.对我来说情况并非如此(相反,它是RecyclerView).

以下是链接,希望它们可以作为参考.

> TextView must not be null
> context must not be null

在对我的代码进行多次检查后,我发誓我已将正确的布局放入.编辑：我导入了kotlinx.android.synthetic.main.^包,我把这个标志放在：^ ${layout}.这是我的一些文件(如果这个帖子太长,请原谅我)：

> MainActivity.kt：AppCompatActivity()^ activity_main.*

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // preparing the app bars
        setSupportActionBar(toolBar)

        // getting ready for the pages
        val pagerAdapter = MainPagerAdapter(
                supportFragmentManager,
                resources.getString(R.string.tab_main),
                resources.getString(R.string.tab_chat)
        )
        pager.adapter = pagerAdapter

        // activating tabs
        tabLayout.setupWithViewPager(pager)

        val toggle = ActionBarDrawerToggle(
                this, mainDrawer, toolbar,
                R.string.navigation_drawer_open,
                R.string.navigation_drawer_close)

        mainDrawer.addDrawerListener(toggle)


        navView.setNavigationItemSelectedListener(this)
        toggle.syncState()

}

> MainPagerAdapter.kt(fm：FragmentManager,private val page1：String,private val page2：String)：FragmentPagerAdapter(fm)

override fun getItem(position: Int): Fragment? {
    return when (position) {
        0 -> MainFragment()
        1 -> ChatFragment()
        else -> null
    }
}

override fun getCount() = 2

override fun getPageTitle(position: Int): CharSequence? {
    return when (position) {
        0 -> page1
        1 -> page2
        else -> null
    }
}

> MainFragment.kt：Fragment()^ content_main.*

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?)
    : View? = inflater.inflate(R.layout.content_main, container)

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    // this is the error
    mainMenu.layoutManager = linearlayoutmanager(this.context)

    mainMenu.adapter = MyAdapter(itemList) {
        toast("${it.name} selected")
    }
}

> MyAdapter.kt：RecyclerView.Adapter< MyAdapter.MyHolder>()^ item_custom.view.*(由Antonio Leiva提供)

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int)
    = GoodsHolder(parent.inflate(R.layout.item_custom))

override fun getItemCount()
    = itemList.size

override fun onBindViewHolder(holder: MyHolder, position: Int)
    = holder.bind(itemList[position], listener)


class MyHolder(v: View): RecyclerView.ViewHolder(v){
    private val item: Item? = null
    private val view = v

    fun bind(item: Item, listener: (Item) -> Unit)
            = with (itemView) {
        imgPic.setimageResource(item.pictureId)
        txtName.text = item.name
        txtPrice.text = item.price.toString()

    setonClickListener { listener(item) }
    }
}

> content_main.xml

<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.MyApp.app.activity.MainActivity"
    >

    <!-- the RecyclerView that caused the runtime error -->
    <android.support.v7.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/mainMenu"/>

</android.support.constraint.ConstraintLayout>

> item_custom.xml(这些代码位于CardView内的LinearLayout内)

<ImageView
    android:id="@+id/imgPic"
    android:layout_width="match_parent"
    android:layout_height="128dp"
    app:srcCompat="@drawable/ic_menu_gallery" />

<TextView
    android:id="@+id/txtName"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Get it while it's hot!"
    android:layout_margin="@dimen/margin_small"
    android:layout_marginTop="@dimen/margin_medium"
    android:maxLines="2"
    android:ellipsize="end"
    android:text/>

<TextView
    android:id="@+id/txtPrice"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="$3.000.000"
    android:layout_marginLeft="@dimen/margin_small"
    android:layout_marginStart="@dimen/margin_small"
    android:layout_marginRight="@dimen/margin_small"
    android:layout_marginEnd="@dimen/margin_small"
    android:layout_marginBottom="@dimen/margin_medium"/>

> ChatFragment.kt：Fragment()(仅包含onCreateView inflating content_main_chat.xml)
> content_main_chat.xml(仅包含TextView)

解决方法:

您尚未在MainFragment.kt文件中初始化RecyclerView.你必须在下面的行之前初始化它：

mainMenu.layoutManager = linearlayoutmanager(this.context)

您可以通过以下行初始化RecyclerView：

var mainMenu = findViewById(R.id.mainMenu) as RecyclerView

你必须根据需要改变它.

Application.Current<PageName>返回null

Application.Current返回null

确保已在App的构造函数中设置了 MainPage 。

type Vacancies struct {
    ID int `json:"id"`
    Title string `json:"title"`
    Logo string `json:"logo"`
    Items []string `json:"items"`
}

func (r *repository) GetVacancies(ctx context.Context) []*Vacancies {
    const queryString = "select json_object('id',vd.id,'title',vd.title,'logo',vd.logo,'items',json_array((select GROUP_CONCAT(json_object('id',id,title,'description',description)) from vacancies as v where department_id = vd.id order by vd.sort))) from vacancy_departments as vd order by vd.sort"
    defer utils.StartRelicDatastoreSegment(
        ctx,newrelic.DatastoreMySQL,"Vacancies.GetVacancies","Select",queryString,).End()

    var result []*Vacancies
    if err := mysql.Client().Slave().Select(&result,queryString); err != nil {
        logger.Get().Error("err while getting vacancies",zap.Error(err))
        return nil
    }

    return result
}

如果仍然无法使用，则可以首先使用以下解决方法。

public App()
{
  InitializeComponent();

  MainPage = new xxxPage();

}

并引用

public static Page RootPage;

public App()
{
  InitializeComponent();

  MainPage = new MainPage();

  App.RootPage = this.MainPage;
}

我们今天的关于EF为Navagation属性返回null和ef添加数据返回id的分享已经告一段落，感谢您的关注，如果您想了解更多关于Android MediaProjection acquisitionLatestImage始终为ImageReader返回Null、android – IllegalArgumentException：savedInstanceState指定为Non-Null为Null、android – IllegalStateException：NavigationDrawer活动中的Fragment内的RecyclerView为null、Application.Current返回null的相关信息，请在本站查询。

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