来源: 互联网  发布时间: 2014-02-18

采用ViewHolder模式提高AdapterView显示的效率
如果对效率要求比较高的话可以采用这种办法，唯一的缺点就是多了一个内部类ViewHolder。

public View getView(int pos, View convertView, ViewGroup parent){ 
            ViewHolder holder;
            if (convertView == null) { 
                holder=new ViewHolder();
                convertView = mInflater.inflate(R.layout.list_item, null); 
                holder.text = (TextView) convertView.findViewById( R.id.text));
                holder.icon = (ImageView) convertView.findViewButId( R.id.icon));
                convertView.setTag(holder); 
                }
            else { 
                holder = (ViewHolder) convertView.getTag(); 
                }
            holder.text.setText(DATA[pos]); 
            holder.icon.setImageBitmap((pos & 1) == 1 ? mIcon1 : mIcon2);
                return convertView;
                } 
 
        static class ViewHolder { 
            TextView text;
            ImageView icon;
            } 

    

    来源: 互联网  发布时间: 2014-02-18

Gallery默认第一项居左
网上找的，暂时用不到没测试过。
Android 中的Gallery控件默认会将第一项居中显示，在某些场景会影响用户体验，分享一下居左的：

/**
* Align the first gallery item to the left.
*
* @param parentView The view containing the gallery widget (we assume the gallery width
* is set to match_parent)
* @param gallery The gallery we have to change
*/
private void alignGalleryToLeft(View parentView, Gallery gallery) {
int galleryWidth = parentView.getWidth();

// We are taking the item widths and spacing from a dimension resource because:
// 1. No way to get spacing at runtime (no accessor in the Gallery class)
// 2. There might not yet be any item view created when we are calling this
// function
int itemWidth = context.getResources()
.getDimensionPixelSize(R.dimen.gallery_item_width);
int spacing = context.getResources()
.getDimensionPixelSize(R.dimen.gallery_spacing);

// The offset is how much we will pull the gallery to the left in order to simulate
// left alignment of the first item
int offset;
if (galleryWidth <= itemWidth) {
offset = galleryWidth / 2 - itemWidth / 2 - spacing;
} else {
offset = galleryWidth - itemWidth - 2 * spacing;
}
offset = 0;

// Now update the layout parameters of the gallery in order to set the left margin
MarginLayoutParams mlp = (MarginLayoutParams) gallery.getLayoutParams();
mlp.setMargins(-offset, mlp.topMargin, mlp.rightMargin, mlp.bottomMargin);
}

http://androidit.diandian.com/post/b8c29a20-e368-11e0-94a3-782bcb32ff27

Android自定义Gallery，实现CoverFlow效果
http://bigcat.easymorse.com/?p=1391

    

    来源: 互联网  发布时间: 2014-02-18

第八节(Activity布局初步一)

一、LinearLayout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <!-- 
	    android:orientation="vertical"- -指定控件排列方向
	    android:layout_width="fill_parent"
	    android:layout_height="fill_parent" 
    -->
    <!-- 
    	android:id="@+id/btn_1"
		android:layout_width="fill_parent"
		android:layout_height="wrap_content"
		android:text="第2行"
		android:gravity="center"- -指定控件的基本位置比如居中、居右等位置
		android:textSize="20pt"- -指定控件当中文本字体大小
		android:background="#aa0000"- -指定控件背景色,使用RGB命名法
		android:padding....- -指定控件内容的边距
		android:layout_weight="2"- -指定控件在布局中占用屏幕的比例
		android:singleLine="true"- -指定控件是的内容是否在同一行中展示
     -->
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    android:layout_weight="5"
    />
<Button
	android:id="@+id/btn_1"
	android:layout_width="fill_parent"
	android:layout_height="wrap_content"
	android:text="第2行第2行第2行第2行第2行第2行第2行第2行第2行第2行第2行第2行第2行第2行"
	android:gravity="top"
	android:textSize="20pt"
	android:background="#aa0000"
	android:paddingLeft="10dip"
	android:paddingTop="1dip"
	android:paddingRight="30dip"
	android:paddingBottom="40dip"
	android:layout_weight="1"
	android:singleLine="true"
/>
</LinearLayout>

 

二、TableLayout

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:stretchColumns="0"
    >
    <!-- android:stretchColumns="0"如果不能撑满窗口,拉伸第0列填满窗口 -->
    <TableRow>
    	<TextView 
    		android:text="column1"
    		android:padding="5dip"
    		android:background="#aa0000"
    	/>
    	<TextView 
    		android:text="column2"
    		android:padding="5dip"
    		android:background="#0000aa"
    		android:layout_gravity="center_vertical"
    	/>
    	<TextView 
    		android:text="column3"
    		android:padding="5dip"
    		android:background="#00aa00"
    	/>
    </TableRow>
    <TableRow>
    	<TextView 
    		android:text="column1"
    		android:padding="5dip"
    	/>
    	<TextView 
    		android:text="column2"
    		android:padding="5dip"
    	/>
    	<TextView 
    		android:text="column3"
    		android:padding="5dip"
    	/>
    </TableRow>
</TableLayout>