Android java.lang.NullPointerException: println 需要一条消息
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java.lang.NullPointerException: println needs a message
提问by Laire
I get the errror: java.lang.NullPointerException: println needs a message when I call this method:
我得到错误：java.lang.NullPointerException：当我调用这个方法时，println需要一条消息：
lst_info = new HashMap<String, String>();
SystemDatabaseHandler db = new SystemDatabaseHandler(getApplicationContext());
lst_info = db.getLstInfo(sql_id);
SystemDatabaseHandler:
系统数据库处理程序：
public HashMap<String , String> getLstInfo(int id){
HashMap<String , String> lst_temp;
lst_temp = new HashMap<String , String>();
String selectQuery = "SELECT * FROM dkr_lst_lst WHERE lst_id = " + id;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
Log.d("sql_id", cursor.getString(0));
lst_temp.put("sql_id", cursor.getString(0));
}while (cursor.moveToNext());
}
cursor.close();
db.close();
return lst_temp;
}
Log.d("sql_id", cursor.getString(0)); returns:
Log.d("sql_id", cursor.getString(0)); 返回：
07-12 11:56:05.603: D/sql_id(13783): 1
07-12 11:56:05.603: D/sql_id(13783): 1
The Log Cat:
原木猫：
07-12 11:56:05.613: D/Database(13783): dbclose(): path = /data/data/de.bodprod.dkr/databases/dkr, handle = 0x4301a8
07-12 11:56:05.613: D/AndroidRuntime(13783): Shutting down VM
07-12 11:56:05.613: W/dalvikvm(13783): threadid=1: thread exiting with uncaught exception (group=0x4001d5a0)
07-12 11:56:05.623: E/AndroidRuntime(13783): FATAL EXCEPTION: main
07-12 11:56:05.623: E/AndroidRuntime(13783): java.lang.RuntimeException: Unable to start activity ComponentInfo{de.bodprod.dkr/de.bodprod.dkr.BosLstDetailMap}: java.lang.NullPointerException: println needs a message
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1872)
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1893)
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.app.ActivityThread.access00(ActivityThread.java:135)
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1054)
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.os.Handler.dispatchMessage(Handler.java:99)
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.os.Looper.loop(Looper.java:150)
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.app.ActivityThread.main(ActivityThread.java:4385)
07-12 11:56:05.623: E/AndroidRuntime(13783): at java.lang.reflect.Method.invokeNative(Native Method)
07-12 11:56:05.623: E/AndroidRuntime(13783): at java.lang.reflect.Method.invoke(Method.java:507)
07-12 11:56:05.623: E/AndroidRuntime(13783): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849)
07-12 11:56:05.623: E/AndroidRuntime(13783): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607)
07-12 11:56:05.623: E/AndroidRuntime(13783): at dalvik.system.NativeStart.main(Native Method)
07-12 11:56:05.623: E/AndroidRuntime(13783): Caused by: java.lang.NullPointerException: println needs a message
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.util.Log.println_native(Native Method)
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.util.Log.d(Log.java:137)
07-12 11:56:05.623: E/AndroidRuntime(13783): at de.bodprod.dkr.BosLstDetailMap.onCreate(BosLstDetailMap.java:43)
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1072)
07-12 11:56:05.623: E/AndroidRuntime(13783): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1836)
07-12 11:56:05.623: E/AndroidRuntime(13783): ... 11 more
07-12 11:56:07.495: D/Process(13783): killProcess, pid=13783
回答by NitroG42
Maybe when you call
也许当你打电话
Log.d("sql_id", cursor.getString(0));
cursor.getString(0)returns null, and then it crashes.
cursor.getString(0)返回 null，然后崩溃。
Try :
尝试 ：
if(cursor.getString(0) != null) {
Log.d("sql_id", cursor.getString(0));
}
Otherwise, show us: de.bodprod.dkr.BosLstDetailMap.onCreate(BosLstDetailMap.java:43)
否则，向我们展示： de.bodprod.dkr.BosLstDetailMap.onCreate(BosLstDetailMap.java:43)
回答by ρяσ?ρ?я K
try as:
尝试如下：
Log.d("sql_id"," " + cursor.getString(0));
instead of
代替
Log.d("sql_id", cursor.getString(0));
beacuse maybe you are passing second parameter in Log.d empty or null
因为也许你在 Log.d 中传递第二个参数为空或空
