android - 我想在将一个 View 拖放到另一个 View 后开始新的 Activity。在 switch case 中我该怎么做？

Question

我已经搜索了一个多星期，但我无法弄清楚如何从案例中开始新 Activity 。

这是来自 android studio 的示例拖放示例代码。我该如何添加？...我想创建一个场景，如果我将一个 View 拖到另一个 View 中，则会启动一个新的 Activity 页面。这是我在互联网上的第一个问题。

我想放弃并且感到沮丧，因为我有一份新手工作机会，除非我这样做，否则我无法接受。

public class DragActivity extends Activity {

/** Called when the activity is first created. */

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_drag);
    findViewById(R.id.myimage1).setOnTouchListener(new MyTouchListener());
    findViewById(R.id.myimage2).setOnTouchListener(new MyTouchListener());
    findViewById(R.id.myimage3).setOnTouchListener(new MyTouchListener());
    findViewById(R.id.myimage4).setOnTouchListener(new MyTouchListener());
    findViewById(R.id.topleft).setOnDragListener(new MyDragListener());
    findViewById(R.id.topright).setOnDragListener(new MyDragListener());
    findViewById(R.id.bottomleft).setOnDragListener(new MyDragListener());
    findViewById(R.id.bottomright).setOnDragListener(new MyDragListener());

}

private final class MyTouchListener implements OnTouchListener {
    public boolean onTouch(View view, MotionEvent motionEvent) {
        if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
            ClipData data = ClipData.newPlainText("", "");
            DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
            view.startDrag(data, shadowBuilder, view, 0);
            view.setVisibility(View.INVISIBLE);
            return true;
        } else {
            return false;
        }
    }
}

class MyDragListener implements OnDragListener {
    Drawable enterShape = getResources().getDrawable(R.drawable.shape_droptarget);
    Drawable normalShape = getResources().getDrawable(R.drawable.shape);

    @Override
    public boolean onDrag(View v, DragEvent event) {
        int action = event.getAction();
        switch (event.getAction()) {
            case DragEvent.ACTION_DRAG_STARTED:
                // do nothing
                break;
            case DragEvent.ACTION_DRAG_ENTERED:
                v.setBackgroundDrawable(enterShape);
                break;
            case DragEvent.ACTION_DRAG_EXITED:
                v.setBackgroundDrawable(normalShape);
                break;
            case DragEvent.ACTION_DROP:
                // Dropped, reassign View to ViewGroup
                View view = (View) event.getLocalState();
                ViewGroup owner = (ViewGroup) view.getParent();
                owner.removeView(view);
                LinearLayout container = (LinearLayout) v;
                container.addView(view);
                view.setVisibility(View.VISIBLE);

                break;
            case DragEvent.ACTION_DRAG_ENDED:
                v.setBackgroundDrawable(normalShape);

            default:
                break;
        }
        return true;
    }

    }
}

Answer 1

我创建了两个 ImageView (红色和灰色)，当拖动红色 View 并放入灰色时，会引发一个新的 Activity。

主 Activity

public class MainActivity extends AppCompatActivity implements View.OnDragListener,
                                                               View.OnTouchListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ImageView left = (ImageView) findViewById(R.id.left);
        ImageView right = (ImageView) findViewById(R.id.right);

        left.setOnTouchListener(this);
        left.setOnDragListener(this);
        right.setOnDragListener(this); // Added a drag listener to the other view

    }

    @Override
    public boolean onDrag(View v, DragEvent event) {

        int action = event.getAction();
        switch (action) {
            case ACTION_DROP: {
                /**
                 * If the item view is the origin return false, reject the drop event
                 */
                if (v.getId() == R.id.left)
                    return false;
                /**
                 * Else accept the event and raise the activity
                 */
                startActivity(new Intent(MainActivity.this, DragDropActivity.class));
            }
        }
        return true;
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {

        if (v.getId() == R.id.right) return false;

        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            //setup drag
            ClipData data = ClipData.newPlainText("", "");
            View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(v);
            v.startDrag(data, shadowBuilder, v, 0);
            return true;
        }
        return false;
    }
}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<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="forkandjoin.draganddrop.MainActivity">

    <ImageView
        android:id="@+id/left"
        android:layout_width="50dip"
        android:layout_height="50dip"
        android:background="#FF0000"
        android:layout_alignParentLeft="true"
        />

    <ImageView
        android:id="@+id/right"
        android:layout_width="50dip"
        android:layout_height="50dip"
        android:background="#929292"
        android:layout_alignParentRight="true"/>

</RelativeLayout>

应用

当您将红色项目放入灰色项目时，会引发一个新的 Activity 。

好好享受吧。