我正在尝试创建一个包含以下组件的新数据库：
以下是数据库助手的代码：
public class ContactsDatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "contactList.db";
private static final String TABLE_NAME = "contact_table";
public static final String COL1 = "ID";
private static final String COL2 = "PERSON_NAME";
private static final String COL3 = "IMAGESOURCE";
private static final String COL4 = "LOCATION";
private static final String COL5 = "UNIQUE_ID";
private Context context;
public ContactsDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1/**version**/);
this.context = context;
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
String createTable = "CREATE TABLE " + TABLE_NAME + "(ID INTEGER PRIMARY KEY AUTOINCREMENT, "
+ " PERSON_NAME TEXT, IMAGESOURCE BLOB, LOCATION TEXT, UNIQUE_ID TEXT)";
sqLiteDatabase.execSQL(createTable);
Log.v("onCreate","Database Created!");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP IF TABLE EXISTS " + TABLE_NAME);
onCreate(db);
Log.v("onUpgrade","Database Created!");
}
public boolean addData(String person_name,int imageSource, LatLng location, String unique_id){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
Log.v("addData","Database Created!");
Gson gson = new Gson();
String gsonLocation = "";
if(location != null) {
gsonLocation = gson.toJson(location, LatLng.class);
}else{
gsonLocation = null;
}
Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), imageSource);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
byte[] image = baos.toByteArray();
contentValues.put(COL2, person_name);
contentValues.put(COL3, image);
contentValues.put(COL4, gsonLocation);
contentValues.put(COL5, unique_id);
long result = db.insert(TABLE_NAME, null, contentValues);
if(result == -1){
return false;
}else{
return true;
}
}
我从其他数据库帮助程序中复制了此代码，并更改了变量。但是，在更改之后，它会导致NullPointerException错误。
以下是从活动向数据库添加数据的代码。
@Override
protected void onResume(){
//Stuff
addcontacts = (FloatingActionButton) findViewById(R.id.fabcontacts);
final ContactsDatabaseHelper contactManager = new ContactsDatabaseHelper(context);
addcontacts.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final AlertDialog.Builder mBuilder = new AlertDialog.Builder(ContactActivity.this);
View mView = getLayoutInflater().inflate(R.layout.inital_contactcommit,null);
mBuilder.setView(mView);
final AlertDialog dialog = mBuilder.create();
dialog.show();
//Get reference to the views in the dialog.
tempName = nameedit.getText().toString();
tempUniqueId = uniqueidedit.getText().toString();
cancelbutton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
dialog.dismiss();
}
});
doneButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final AlertDialog.Builder m2Builder = new AlertDialog.Builder(ContactActivity.this);
View m2View = getLayoutInflater().inflate(R.layout.contactadd_dialog,null);
m2Builder.setView(m2View);
final AlertDialog dialog2 = m2Builder.create();
//Get reference to views
uniqueidfinal.setText(tempUniqueId);
nameedit2.setText(tempName);
dialog2.show();
cancelbutton2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
dialog.dismiss();
}
});
doneButton2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
boolean insertData = contactManager.addData(tempName,R.drawable.angelinajolie,null,"hello");
if (insertData == true) {
Toast.makeText(ContactActivity.this, "Data Successfully Inserted!", Toast.LENGTH_LONG).show();
Log.v("Database","Data Successfully Inserted!");
} else {
Toast.makeText(ContactActivity.this, "Something went wrong :(.", Toast.LENGTH_LONG).show();
Log.v("Database","Data Insert Failed!");
}
}
});
}
});
}
});
}
以下是错误日志：
08-26 15:28:15.940 6935-6935/com.example.android.gatheraround E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.gatheraround, PID: 6935
java.lang.RuntimeException: Unable to resume activity {com.example.android.gatheraround/com.example.android.gatheraround.ContactActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2788)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2817)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2250)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
at com.example.android.gatheraround.ContactsDatabaseHelper.<init>(ContactsDatabaseHelper.java:41)
at com.example.android.gatheraround.ContactActivity.onResume(ContactActivity.java:53)
at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1192)
at android.app.Activity.performResume(Activity.java:5310)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2778)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2817)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2250)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)