共享元素不能为空 - 共享元素活动转换

Question

我一直在尝试实现共享元素转换，但每次点击转换时都会出现“java.lang.IllegalArgumentException：共享元素不能为空”的错误。请帮忙。

下面是MainActivity onCreate方法的代码，请检查我的代码。

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

    imageView = findViewById(R.id.image);

    recList = (RecyclerView)findViewById(R.id.RecView);
    recList.setHasFixedSize(true);

    recList.addOnItemTouchListener(
            new MyOnClickListener(this, new MyOnClickListener.OnItemClickListener() {
                @Override public void onItemClick(View view, int position) {
                    Intent intent  = new Intent(MainActivity.this, DetailsActivity.class);

                    String transitionName = getString(R.string.transitionName);



                    ActivityOptionsCompat options = ActivityOptionsCompat.
                            makeSceneTransitionAnimation(MainActivity.this, imageView, transitionName);

                    startActivity(intent, options.toBundle());
                }
            })
    );

这是recyclerView的点击监听器。

public class MyOnClickListener implements RecyclerView.OnItemTouchListener {

private OnItemClickListener mListener;

public interface OnItemClickListener {
    void onItemClick(View view, int position);
}

GestureDetector mGestureDetector;


@Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {

}


public MyOnClickListener(Context context, OnItemClickListener listener) {
    mListener = listener;
    mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            return true;
        }
    });
}

@Override
public boolean onInterceptTouchEvent(RecyclerView view, MotionEvent e) {
    View childView = view.findChildViewUnder(e.getX(), e.getY());
    if (childView != null && mListener != null && mGestureDetector.onTouchEvent(e)) {
        mListener.onItemClick(childView, view.getChildAdapterPosition(childView));
    }
    return false;
}

@Override
public void onTouchEvent(RecyclerView view, MotionEvent motionEvent) {
}
}

图片的转换名称是相同的。这里的错误修复在共享元素中的活动转换中有故障并不是问题所在。

我的卡片的xml...

<?xml version="1.0" encoding="utf-8"?>

>

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/image"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:scaleType="centerCrop"
        android:src="@drawable/littlefractal"
        android:transitionName="@string/transitionName" />

    <TextView
        android:id="@+id/txt_first_name"
        android:layout_width="match_parent"
        android:layout_height="20dp"

        android:layout_alignParentEnd="true"
        android:layout_centerVertical="true"
        android:layout_toEndOf="@+id/image"
        android:text="FirstName"
        android:textColor="@color/colorPrimaryDark"
        android:textSize="16sp"

       />

</RelativeLayout>

The xml of the destination activity.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center">

    <ImageView
        android:id="@+id/image"
        android:layout_width="150dp"
        android:layout_height="150dp"
        android:scaleType="centerCrop"
        android:src="@drawable/littlefractal"
        android:transitionName="@string/transitionName" />


</LinearLayout>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_marginStart="40dp">

        <TextView
            android:id="@+id/txt_first_name_details"
            android:layout_width="wrap_content"
            android:layout_height="40dp"
            android:gravity="center_vertical"
            android:text="FirstName"
            android:textColor="@color/colorPrimaryDark"
            android:textSize="16sp"
            />


        <TextView
            android:id="@+id/txt_last_name"
            android:layout_width="wrap_content"
            android:layout_height="40dp"

            android:gravity="center_vertical"
            android:text="LastName"
            android:textColor="@color/colorPrimaryDark"
            android:textSize="16sp"
            android:layout_marginStart="10dp"/>

    </LinearLayout>




    <TextView
        android:id="@+id/txt_address"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"

        android:gravity="center_vertical"
        android:padding="10dp"
        android:text="Address"
        android:textColor="@color/colorPrimary"
        android:textSize="16sp"
        android:layout_marginStart="30dp"/>

    <TextView
        android:id="@+id/txt_phone"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"

        android:gravity="center_vertical"
        android:padding="10dp"
        android:text="Phone"
        android:textColor="@color/colorPrimary"
        android:textSize="16sp"
        android:layout_marginStart="30dp"/>

</LinearLayout>

Go easy. Still learning this whole android thing. Peace and appreciation.

- tlagreca

---

只需正确检查可能 getString(R.string.transitionName) 是否为空。可以通过 getResources().getString(R.string.transitionName) 访问它。还要检查 xml 文件中的 ImageView 必须设置相同的 android:transitionName 值。 - Piyush

是的，我检查过了。它们都是一样的。调试器告诉我imageView为空。转换名称都没问题。 - tlagreca

这是ImageViews。 - tlagreca

在日志中打印_transitionName_ - Piyush

过渡名称是：personDetails。它是红色的，但是正确的。 - tlagreca

Answer 1

出现此异常是因为imageView为空。您需要从RecyclerView项目中获取imageView。请尝试以下操作：

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

recList = (RecyclerView)findViewById(R.id.RecView);
recList.setHasFixedSize(true);

recList.addOnItemTouchListener(
        new MyOnClickListener(this, new MyOnClickListener.OnItemClickListener() {
            @Override public void onItemClick(View view, int position) {
                Intent intent  = new Intent(MainActivity.this, DetailsActivity.class);
                String transitionName = getString(R.string.transitionName);
                View transitionView = view.findViewById(R.id.image);
                ViewCompat.setTransitionName(transitionView, transitionName);

                ActivityOptionsCompat options = ActivityOptionsCompat.
                        makeSceneTransitionAnimation(MainActivity.this, transitionView, transitionName);

                startActivity(intent, options.toBundle());
            }
        })
);

- princeparadoxes