Question

我正在尝试获取设备上已安装应用程序的列表，然后在列表中显示其名称但是，当我运行我的代码时，它显示不幸的是，Lister已被停止 我在onCreate方法中的代码是： -

PackageManager pm=this.getPackageManager();
        List<ApplicationInfo> list=pm.getInstalledApplications(0);
        ListView lv=(ListView)findViewById(R.id.listView1);
        ArrayList<String> al=new ArrayList<String>();
        for(ApplicationInfo app:list)
        {
            String appN=pm.getApplicationLabel(app).toString();
            al.add(appN);

        }
        ArrayAdapter<String> arr=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,android.R.id.text1,al);
        lv.setAdapter(arr);
        setContentView(R.layout.activity_sec);

和我的 activity_sec.xml 代码是： -

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="top"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.gestureview.Sec" >

    <ListView
        android:id="@+id/listView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="40dp" >
    </ListView>

</RelativeLayout>

我的Log Cat是： -

06-19 04:33:53.234: E/AndroidRuntime(1205): FATAL EXCEPTION: main
06-19 04:33:53.234: E/AndroidRuntime(1205): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.gestureview/com.example.gestureview.Sec}: java.lang.NullPointerException
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.os.Looper.loop(Looper.java:137)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.app.ActivityThread.main(ActivityThread.java:5041)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at java.lang.reflect.Method.invokeNative(Native Method)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at java.lang.reflect.Method.invoke(Method.java:511)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at dalvik.system.NativeStart.main(Native Method)
06-19 04:33:53.234: E/AndroidRuntime(1205): Caused by: java.lang.NullPointerException
06-19 04:33:53.234: E/AndroidRuntime(1205):     at com.example.gestureview.Sec.onCreate(Sec.java:33)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.app.Activity.performCreate(Activity.java:5104)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-19 04:33:53.234: E/AndroidRuntime(1205):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
06-19 04:33:53.234: E/AndroidRuntime(1205):     ... 11 more

创建ListView似乎一定存在问题。

Answer 1

首先应该设置内容而不是调用ListView

PackageManager pm=this.getPackageManager();
    List<ApplicationInfo> list=pm.getInstalledApplications(0);
    setContentView(R.layout.activity_sec);    ///call this Line here
    ListView lv=(ListView)findViewById(R.id.listView1);
    ArrayList<String> al=new ArrayList<String>();
    for(ApplicationInfo app:list)
    {
        String appN=pm.getApplicationLabel(app).toString();
        al.add(appN);

    }
    ArrayAdapter<String> arr=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,android.R.id.text1,al);
    lv.setAdapter(arr);

Answer 2

这也很有效

                final PackageManager pm = mParentActivity.getPackageManager();
                List<ApplicationInfo> packages = pm.getInstalledApplications(0);

                for (ApplicationInfo packageInfo : packages) {
                    // get the UID for the selected app
                    int UID = packageInfo.uid;
                    String package_name = packageInfo.packageName;
                    ApplicationInfo app = null;
                    try {
                        app = pm.getApplicationInfo(package_name, 0);
                    } catch (NameNotFoundException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }

                    String name = (String) pm.getApplicationLabel(app);
                    Drawable icon = pm.getApplicationIcon(app);
                    final SmsDetailsPojo dataItem = new SmsDetailsPojo();
                    dataItem.setContactNum(name);
                    dataItem.setDrawable(icon);

                if((app.flags & ApplicationInfo.FLAG_UPDATED_SYSTEM_APP) == 1) {
                        // updated system apps

                    } else if ((app.flags & ApplicationInfo.FLAG_SYSTEM) == 1) {
                        // system apps

                    } else {

                        arrayUserInstalledApps.add(dataItem);

}

创建和填充ListView时出错

2 个答案: