Activity的使用

下面会主要介绍三种Activity的用法：

LauncherActivity的作用在于形成一个列表,点击列表项时，可产生相应的intent进入到其他的Activity界面。

既然是列表，我们当然需要一个适配器来设置列表项的内容，由于LauncherActivity的一个列表项和一个class相关联，所以才能达到点击一个列表项就启动一个Activity的功能。因此还需要一个class数组，用来放要启动的Activity。最后要重写intentForPosition()方法。

具体代码如下：

public class MainActivity extends LauncherActivity {    //定义列表项显示的内容，最好为两个Activity的名称    String[] names = {"设置程序参数" , "查看星际兵种"};    //定义两个Activity对应的实现类    Class<?>[] clazzs ={PreferenceActivityTest.class , ExpandableListActivityTest.class};    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this , R.layout.support_simple_spinner_dropdown_item, names);        //设置该窗口列表所需的adapter        setListAdapter(adapter);    }    //根据列表项来返回指定Acticity对应的intent    @Override    public Intent intentForPosition(int position){        return new Intent(MainActivity.this , clazzs[position]);    }}

上面用到的两个Activity

ExpandableListActivityTest:

ExpandableListActivity的子类，用于显示一个可展开的列表窗口

PerferenceActivity的子类，用于显示一个设置选项参数并保存的窗口
res\xml\preferences.xml

<?xml version="1.0" encoding="utf-8"?><PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">    <RingtonePreference android:ringtoneType="all"        android:title="设置铃声"        android:summary="选择铃声（测试RingtonePreference）"        android:showDefault="true"        android:key="ring_key"        android:showSilent="true"></RingtonePreference>    <PreferenceCategory android:title="个人信息设置组">        <EditTextPreference            android:key="name"            android:title="填写用户名"            android:summary="填写您的用户名（测试EditTextPreference）"            android:dialogTitle="您所使用的用户名为："/>        <ListPreference            android:key="gender"            android:title="性别"            android:summary="选择性别(测试ListPreference)"            android:dialogTitle="ListPreference"            android:entries="@array/gender_name_list"            android:entryValues="@array/gender_name_value"/>    </PreferenceCategory>    <PreferenceCategory android:title="系统功能设置组">        <CheckBoxPreference            android:key="autoSave"            android:title="自动保存进度"            android:summaryOn="开启"            android:summaryOff="关闭"            android:defaultValue="true"/>    </PreferenceCategory></PreferenceScreen>

PerferenceActivityTest.java

public class PreferenceActivityTest extends PreferenceActivity{    @Override    public void onCreate(Bundle savedInstanceState){        super.onCreate(savedInstanceState);        addPreferencesFromResource(R.xml.preferences);    }}

ExpandableListActivityTest.java

public class ExpandableListActivityTest extends ExpandableListActivity {    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        ExpandableListAdapter adapter=new BaseExpandableListAdapter() {            int[] logos = new int[]{                    R.drawable.p,                    R.drawable.z,                    R.drawable.t            };            private String[] armTypes = new String[]{                    "神族兵种","虫族兵种","人族兵种"            };            private String[][] arms=new String[][]{                    {"狂战士","龙骑士","黑暗圣堂"},                    {"小狗","刺蛇","飞龙","自爆飞机"},                    {"机枪兵","护士","幽灵"}            };<span style="white-space:pre"></span>    //获取指定组位置，指定子列表项数据            @Override            public Object getChild(int groupPosition, int childPosition) {                return arms[groupPosition][childPosition];            }            @Override            public long getChildId(int groupPosition, int childPosition) {                return childPosition;            }            @Override            public int getChildrenCount(int groupPosition) {                return arms[groupPosition].length;            }            private TextView getTextView(){                AbsListView.LayoutParams lp=new AbsListView.LayoutParams(                        ViewGroup.LayoutParams.MATCH_PARENT,64);                TextView textView=new TextView(ExpandableListActivityTest.this);                textView.setLayoutParams(lp);                textView.setPadding(36,0,0,0);                textView.setTextSize(20);                return textView;            }<span style="white-space:pre"></span>    //该方法决定每个子选项的外观            @Override            public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {                TextView textView = getTextView();                textView.setText(getChild(groupPosition,childPosition).toString());                return textView;            }<span style="white-space:pre"></span>    //获取指定组位置处的组数据            @Override            public Object getGroup(int groupPosition) {                return armTypes[groupPosition];            }            @Override            public int getGroupCount() {                return armTypes.length;            }            @Override            public long getGroupId(int groupPosition) {                return groupPosition;            }<span style="white-space:pre"></span>    //该方法决定每个组选项的外观            @Override            public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {                LinearLayout ll=new LinearLayout(ExpandableListActivityTest.this);                ll.setOrientation(0);                ImageView logo=new ImageView(ExpandableListActivityTest.this);                logo.setImageResource(logos[groupPosition]);                ll.addView(logo);                TextView textView= getTextView();                textView.setText(getGroup(groupPosition).toString());                ll.addView(textView);                return ll;            }            @Override            public boolean isChildSelectable(int groupPosition, int childPosition) {                return true;            }            @Override            public boolean hasStableIds() {                return true;            }        };<span style="white-space:pre"></span>//设置该窗口显示列表        setListAdapter(adapter);    }}