Question

我在Android中使用ListView创建此类

public class HBSListView extends ListActivity;

当我点击列表中的项目时，我想转到下一个ListActivity，显示上一个列表中点击项目的相关详细信息。

lv.setOnItemClickListener( new OnItemClickListener() {
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {              
        @SuppressWarnings("unchecked")
        HashMap<String, String> o = (HashMap<String, String>) lv.getItemAtPosition(position);                   

        Intent a = new Intent(iTeam.Ufinder.Application.HBS.HBSDetailView.class.getName()); 
        a.putExtra("store_id", o.get("id")); 
        startActivity(a); 

        // When I use above code it is not working. I want to pass ID also.

        // This works but i do not know how to pass ID this way.
        // startActivity(new Intent("iTeam.Ufinder.Application.HBSDETAILVIEW"));
    }
});

public class HBSDetailView extends ListActivity这是我要移动的课程。

Mainfest文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="iTeam.Ufinder.Application"
  android:versionCode="1"
  android:versionName="1.0">
<uses-sdk android:minSdkVersion="10" />

<application android:icon="@drawable/icon" android:label="@string/app_name">
    <activity android:name=".Startup"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
     <activity android:name=".main"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="iTeam.Ufinder.Application.CLEARSCREEN" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>
    <activity android:name="iTeam.Ufinder.Application.MANAGEMENT.Management"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="iTeam.Ufinder.Application.MANAGEMENT" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>
    <activity android:name="iTeam.Ufinder.Application.HBS.HBSListView"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="iTeam.Ufinder.Application.HBSLISTVIEW" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>
    <activity android:name="iTeam.Ufinder.Application.HBS.HBSDetailView"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="iTeam.Ufinder.Application.HBSDETAILVIEW" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>

</application>
<uses-permission android:name="android.permission.INTERNET" />

这是Exception：

04-15 13：04：43.901：ERROR / AndroidRuntime（1417）： java.lang.RuntimeException：无法实例化活动 ComponentInfo {iTeam.Ufinder.Application / iTeam.Ufinder.Application.HBS.HBSDetailView}：显示java.lang.NullPointerException

Answer 1

当您像这样创建Intent时

Intent a = new Intent(iTeam.Ufinder.Application.HBS.HBSDetailView.class.getName());

您使用类名的操作名称创建它。你需要像这样创建Intent：

Intent a = new Intent(HBSListView.this, iTeam.Ufinder.Application.HBS.HBSDetailView.class);

区别在于呼叫签名。第一个是String类型的一个参数。它代表使用指定的操作创建Intent。第二个是关于Context和Class个参数。它用于创建Intent以在指定的上下文中调用指定的类。

同时检查o不为空。

修改

好吧，如果你想以这种方式开展活动......

Intent a = new Intent("iTeam.Ufinder.Application.HBSDETAILVIEW"); a.putExtra("store_id", o.get("id")); startActivity(a);

上面的代码必须按照您的预期工作....

Answer 2

Bundle bundle = new Bundle();
ListAdapter adapter = (new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,list1));
list.setAdapter(adapter);

list.setOnItemClickListener(new OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> arg0, View v,int position, long id) {
        HashMap<String, String> o = (HashMap<String, String>) lv.getItemAtPosition(position);

        if (position == 0) {
            bundle.putString("store_id", o.get("id"));
            Intent inten = new Intent("Activity name which is you must define in manifest file"); 
            inten.putExtras(bundle);

            startActivity(inten);
        }

        if(position==1) {
            //write your code for when second item of listview clicked
        }

        .....

    }
});

将您的Activity添加到清单文件中：

<activity
    android:name=".className"
    android:label="@string/app_name" >
    <intent-filter>
        <action android:name="com.test.ACTIVITY" />
        //use this name when you want to run this activty

        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>
</activity>

从一个ListView活动移动到另一个ListView活动

2 个答案: