2011-8-13 0:35:15
2011-8-13 0:35:15
intent = new Intent().setClass(this, NetworkActivity.class);
spec = tabHost.newTabSpec("network").setIndicator("Network",null)
.setContent(intent);
tabHost.addTab(spec);
intent = new Intent().setClass(this, ContentActivity.class);
spec = tabHost.newTabSpec("content").setIndicator("Content",null)
.setContent(intent);
tabHost.addTab(spec);
intent = new Intent().setClass(this, PlaylistActivity.class);
spec = tabHost.newTabSpec("playlist").setIndicator("Playlist",null)
.setContent(intent);
tabHost.addTab(spec);
创建了3个tab
关联了3个activity
今天给大家讲解一下BaseAdapter(基础适配器）的用法，适配器的作用主要是用来给诸如(Spinner,ListView,GridView)来填充数据的。
而(Spinner,ListView,GridView)都有自己的适配器(记起来麻烦)。但是BaseAdapter（一招鲜）对他们来说却是通用的，为什么这么说呢，首先我们看一下API文档:
我们看一下BaseAdapter已经实现了ListAdapter和SpinnerAdapter的接口，而GridView的适配器是实现了ListAdapter接口，只不过是二维的。所以说BaseAdapter对他们三者来说是通用的。
下面我来说一下BaseAdapter的主要用法.就是我们定义一个类(如：MyAdapter)而这个类继承BaseAdapter.因为它是implements了ListAdapter和SpinnerAdapter的接口，
所以要实现里面的方法，代码如下(未作任何改动的）：
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private
class MyAdapter extends BaseAdapter{
@Override
public
int getCount() {
// TODO Auto-generated method stub
return
0;
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return
null;
}
@Override
public
long getItemId(int position) {
// TODO Auto-generated method stub
return
0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
return
null;
}
}
private class MyAdapter extends BaseAdapter{
@Override public int getCount()
{ // TODO Auto-generated method stub return 0; }
@Override public Object getItem(int arg0) {
// TODO Auto-generated method stub return null; }
@Override public long getItemId(int position) {
// TODO Auto-generated method stub return 0;
} @Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
return null; }
}
为了便于大家理解，老规矩写一个简单的Demo,大家按我的步骤来就OK了.
第一步:新建一个Android工程命名为BaseAdapterDemo.
第二步:修改main.xml代码如下:
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<?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"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Welcome to Mr Wei's Blog"
/>
<Spinner
android:id="@+id/spinner"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<ListView
android:id="@+id/listview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<GridView
android:id="@+id/gridview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</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" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Welcome to Mr Wei's Blog" /> <Spinner android:id="@+id/spinner" android:layout_width="fill_parent" android:layout_height="wrap_content" /> <ListView android:id="@+id/listview" android:layout_width="fill_parent" android:layout_height="wrap_content" /> <GridView android:id="@+id/gridview" android:layout_width="fill_parent" android:layout_height="wrap_content" /></LinearLayout>
第三步:修该BaseAdapterDemo.java代码如下:
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package com.tutor.baseadapter;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ListView;
import android.widget.Spinner;
import android.widget.TextView;
public
class BaseAdapterDemo extends Activity {
private Spinner mSpinner;
private ListView mListView;
private GridView mGridView;
private MyAdapter mMyAdapter;
@Override
public
void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setupViews();
}
public
void setupViews(){
mMyAdapter = new MyAdapter();
mSpinner = (Spinner)findViewById(R.id.spinner);
mSpinner.setAdapter(mMyAdapter);
mListView = (ListView)findViewById(R.id.listview);
mListView.setAdapter(mMyAdapter);
mGridView = (GridView)findViewById(R.id.gridview);
mGridView.setAdapter(mMyAdapter);
mGridView.setNumColumns(2);
}
//定义自己的适配器,注意getCount和getView方法
private
class MyAdapter extends BaseAdapter{
@Override
public
int getCount() {
// 这里我就返回10了，也就是一共有10项数据项
return
10;
}
@Override
public Object getItem(int arg0) {
return arg0;
}
@Override
public
long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// position就是位置从0开始，convertView是Spinner,ListView中每一项要显示的view
//通常return 的view也就是convertView
//parent就是父窗体了，也就是Spinner,ListView,GridView了.
TextView mTextView = new TextView(getApplicationContext());
mTextView.setText("BaseAdapterDemo");
mTextView.setTextColor(Color.RED);
return mTextView;
}
}
}
package com.tutor.baseadapter;import android.app.Activity;import android.graphics.Color;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.GridView;import android.widget.ListView;import android.widget.Spinner;import android.widget.TextView;public class BaseAdapterDemo extends Activity { private Spinner mSpinner; private ListView mListView; private GridView mGridView; private MyAdapter mMyAdapter; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); setupViews(); } public void setupViews(){ mMyAdapter = new MyAdapter(); mSpinner = (Spinner)findViewById(R.id.spinner); mSpinner.setAdapter(mMyAdapter); mListView = (ListView)findViewById(R.id.listview); mListView.setAdapter(mMyAdapter); mGridView = (GridView)findViewById(R.id.gridview); mGridView.setAdapter(mMyAdapter); mGridView.setNumColumns(2); } //定义自己的适配器,注意getCount和getView方法 private class MyAdapter extends BaseAdapter{ @Override public int getCount() { // 这里我就返回10了，也就是一共有10项数据项 return 10; } @Override public Object getItem(int arg0) { return arg0; } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { // position就是位置从0开始，convertView是Spinner,ListView中每一项要显示的view //通常return 的view也就是convertView //parent就是父窗体了，也就是Spinner,ListView,GridView了. TextView mTextView = new TextView(getApplicationContext()); mTextView.setText("BaseAdapterDemo"); mTextView.setTextColor(Color.RED); return mTextView; } }}
第四步:运行程序效果图如下:
效果图一:
效果图二：
等等，平时我在这里就和大家告别了，今天还没完呵呵，因为下面是我们的重点了，我们平常看的应用列表什么的，不是单单的一个TextView就可以了事的，所以我们可以在Layout里事先 定义好布局。这里我新建了一个名叫baseadapter_provider.xml文件，代码如下:
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/icon"
/>
<TextView
android:id="@+id/textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="BaseAdapter"
/>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="fill_parent" > <ImageView android:id="@+id/imageView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/icon" /> <TextView android:id="@+id/textview" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="BaseAdapter" /></LinearLayout>
将getView()方法修改如下:
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@Override
public View getView(int position, View convertView, ViewGroup parent) {
// position就是位置从0开始，convertView是Spinner,ListView中每一项要显示的view
//通常return 的view也就是convertView
//parent就是父窗体了，也就是Spinner,ListView,GridView了.
// TextView mTextView = new TextView(getApplicationContext());
// mTextView.setText("BaseAdapterDemo");
// mTextView.setTextColor(Color.RED);
// return mTextView;
//LayoutInflater不会的参照我的 Android 高手进阶教程(五)
convertView = LayoutInflater.from(getApplicationContext()).inflate
(R.layout.baseadapter_provider,null);
TextView mTextView = (TextView)convertView.findViewById(R.id.textview);
mTextView.setText("BaseAdapterDemo" + position);
mTextView.setTextColor(Color.RED);
return convertView;
}
@Override public View getView(int position, View convertView, ViewGroup parent) { // position就是位置从0开始，convertView是Spinner,ListView中每一项要显示的view //通常return 的view也就是convertView //parent就是父窗体了，也就是Spinner,ListView,GridView了.// TextView mTextView = new TextView(getApplicationContext());// mTextView.setText("BaseAdapterDemo");// mTextView.setTextColor(Color.RED);// return mTextView; //LayoutInflater不会的参照我的 Android 高手进阶教程(五) convertView = LayoutInflater.from(getApplicationContext()).inflate (R.layout.baseadapter_provider,null); TextView mTextView = (TextView)convertView.findViewById(R.id.textview); mTextView.setText("BaseAdapterDemo" + position); mTextView.setTextColor(Color.RED); return convertView; }
再次运行看一下效果图如下:
Ok,搞定了，呵呵，到这里我就要和大家 说再见了，大家 有什么不明白的地方可以留言，要源码的留下邮箱。thx~