Question

我试图在SQLite数据库中搜索并在ListView中显示结果，但我无法得到我想要的结果。它返回类似{1222233333,0909098886}的东西，这不是我正在寻找的东西。结果应该是这样的，在listView上相互低于：

1222233333

0909098886

以下代码位于DBAdapter中。

public ArrayList<String> getMeterNUmber1(String Date) throws SQLException
{
    String[] whereArgs = new String[]{Date};

    Cursor mCursor = db.rawQuery("SELECT MeterNumber FROM " + SCAN_TABLE + " WHERE  Date = ?",whereArgs);

    ArrayList<String> results = new ArrayList<String>();
    while (mCursor.moveToNext()) {
        results.add(mCursor.getString(0));
    }

    return results;
}

在本课程中，我使用sharedPreferences存储结果并将其传递给下一个类，如下所示：

SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
SharedPreferences.Editor editor = settings.edit();
editor.putString("Shareusername",dbUser.getMeterNUmber1(ss).toStrin());
editor.commit();

这就是我尝试在ListView中显示结果的方式：

String sharedUsername;
SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
sharedUsername = settings .getString("Shareusername","null");

String [] value =  new String[] {sharedUsername};

listView = (ListView) findViewById(R.id.mylist);

pojoArrayList = new ArrayList<PojoClass>();
customerListAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,value);
listView.setAdapter(customerListAdapter);

如果有什么我做错了，请帮助我。

日志

01-18 21:17:44.405: E/AndroidRuntime(4249): FATAL EXCEPTION: main
01-18 21:17:44.405: E/AndroidRuntime(4249): java.lang.RuntimeException: Unable to start activity ComponentInfo{scann.barcode.scan/scann.barcode.scan.Result}: java.lang.NullPointerException
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.os.Looper.loop(Looper.java:137)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.app.ActivityThread.main(ActivityThread.java:5039)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at java.lang.reflect.Method.invokeNative(Native Method)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at java.lang.reflect.Method.invoke(Method.java:511)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at dalvik.system.NativeStart.main(Native Method)
01-18 21:17:44.405: E/AndroidRuntime(4249): Caused by: java.lang.NullPointerException
01-18 21:17:44.405: E/AndroidRuntime(4249):     at scann.barcode.scan.DBAdapter.getMeterNUmber1(DBAdapter.java:272)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at scann.barcode.scan.Result.onCreate(Result.java:58)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.app.Activity.performCreate(Activity.java:5104)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
01-18 21:17:44.405: E/AndroidRuntime(4249):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
01-18 21:17:44.405: E/AndroidRuntime(4249):     ... 11 more

Answer 1

您需要将从SharedPreferences检索到的字符串拆分为String数组，以便在ListView中显示为：

String[] value=sharedUsername.split(",");

// Your code here...

无需在ArrayList中存储SharedPreferences，只需将日期存储在SharedPreferences中：

SharedPreferences settings =
    PreferenceManager.getDefaultSharedPreferences(
        getApplicationContext());
SharedPreferences.Editor editor = settings.edit();
editor.putString("datestr",ss);
editor.commit();

现在，当您想要在ListView中将其显示为：

时，使用日期从数据库中检索数据

String sharedUsername;
SharedPreferences settings =
    PreferenceManager.getDefaultSharedPreferences(this);
shareddate = settings .getString("datestr","null");

ArrayList<String> sharedUsernamearr=null;
if(shareddate !=null){
   sharedUsernamearr=dbUser.getMeterNUmber1(shareddate);
}
else{
  // Do your code here
}

listView = (ListView) findViewById(R.id.mylist);

pojoArrayList = new ArrayList<PojoClass>();
if(sharedUsernamearr !=null){
    customerListAdapter = new ArrayAdapter<String>(this,
                                  android.R.layout.simple_list_item_1,
                                  sharedUsernamearr);
    listView.setAdapter(customerListAdapter);
}
else{
    // Add your code here....
}

从listView显示多个值

1 个答案: