Question

我正在为我的应用程序创建一个拖放功能，现在我正在通过一个教程让我习惯了基础知识。我希望能够在我的真实设备上运行我的应用程序，但该版本不支持4.0及更高版本（因为拖放使用Gridlayout）。但它支持API 8。

我环顾四周，注意到人们正在使用支持v7 gridlayout来支持较小的版本。如何在我的应用程序中实现此功能？我在drag_and_drop_app.xml上收到错误：

<?xml version="1.0" encoding="utf-8"?>
<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:columnCount="2"
android:columnWidth="300dp"
android:orientation="vertical"
android:rowCount="2"
android:stretchMode="columnWidth" > 

<LinearLayout
    android:id="@+id/topleft"
    android:layout_width="160dp"
    android:layout_height="200dp"
    android:layout_column="0"
    android:layout_row="0"
    android:background="@drawable/shape" >

    <ImageView
        android:id="@+id/myimage1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_column="0"
        android:layout_row="0"
        android:src="@drawable/ic_launcher" />
</LinearLayout>

<LinearLayout
    android:id="@+id/topright"
    android:layout_width="160dp"
    android:layout_height="200dp"
    android:layout_column="1"
    android:layout_row="0"
    android:background="@drawable/shape" >

    <ImageView
        android:id="@+id/myimage2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_column="0"
        android:layout_row="0"
        android:src="@drawable/ic_launcher" />
</LinearLayout>

<LinearLayout
    android:id="@+id/bottomleft"
    android:layout_width="160dp"
    android:layout_height="200dp"
    android:layout_column="0"
    android:layout_row="1"
    android:background="@drawable/shape" >

    <ImageView
        android:id="@+id/myimage3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" />
</LinearLayout>

<LinearLayout
    android:id="@+id/bottomright"
    android:layout_width="160dp"
    android:layout_height="200dp"
    android:layout_column="1"
    android:layout_row="1"
    android:background="@drawable/shape" >

    <ImageView
        android:id="@+id/myimage4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_column="0"
        android:layout_row="0"
        android:src="@drawable/ic_launcher" />
</LinearLayout>

</GridLayout>

和Drag_and_Drop_App.java：

package com.example.awesomefilebuilderwidget;

import android.app.Activity;
import android.content.ClipData;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.DragEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.DragShadowBuilder;
import android.view.View.OnDragListener;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.widget.LinearLayout;

public class Drag_and_Drop_App extends Activity {
/** Called when the activity is first created. */

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.drag_and_drop_app);
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

我刚改变了这句话：

<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"

到

<android.support.v7.widget.GridLayout xmlns:android="http://schemas.android.com/apk/res/android"

带有相应的结束标记！

Gridlayout支持小于4.0的版本

1 个答案: