FHNe0uxJ

1Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.database.sqlite.SQLiteDatabase.execSQL(java.lang.String)' on a null object reference
2	
3public class UniversityFinderDB  extends SQLiteOpenHelper{
4
5private static final int DATABASE_VERSION= 1;
6static final String DATABASE_NAME="universities.db";
7private static final String TABLE_NAME="universityFinder";
8
9private static final String COLUMN_UNIVID="univId";
10private static final String COLUMN_UNIVERSITYNAME="univName";
11private static final String COLUMN_SCORE="score";
12
13SQLiteDatabase db;
14
15
16
17
18private static final String TABLE_CREATE = "create table universityFinder (univId integer primary key  not null, univName varchar not null, score integer not null);";
19
20public UniversityFinderDB(Context context) {
21    super(context, DATABASE_NAME,null ,DATABASE_VERSION);
22}
23
24@Override
25public void onCreate(SQLiteDatabase database) {
26
27    database.execSQL(TABLE_CREATE);
28
29
30}
31
32
33
34public void executeEventInsert(String name, String score){
35    String query="INSERT INTO universityFinder(univName, score) VALUES('"+name+"','"+score+"');";
36    db.execSQL(query);
37}
38
39
40
41
42public ArrayList<HashMap<String,String>> executeSelectEvents(int input){
43    String query="select * from "+TABLE_NAME+ " where " +COLUMN_SCORE+" >="+input;
44    Cursor cursor= db.rawQuery(query,null);
45    ArrayList<HashMap<String,String>> events=new ArrayList<>();
46    while (cursor.moveToNext()){
47        HashMap<String,String> event=new HashMap<>();
48
49        String colUniversityId=cursor.getColumnName(0);
50        String colUniversityIdValue=cursor.getString(0);
51        String colUniversityName=cursor.getColumnName(1);
52        String colUniversityValue=cursor.getString(1);
53
54
55        event.put(colUniversityId,colUniversityIdValue);
56        event.put(colUniversityName,colUniversityValue);
57        events.add(event);
58    }
59    return events;
60}
61
62
63@Override
64public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
65
66    String query = "DROP TABLE IF EXISTS "+TABLE_NAME;
67    db.execSQL(query);
68}
69
70
71}
72	
73public class ListviewFinderUniversities extends AppCompatActivity {
74
75
76UniversityFinderDB myDB;
77ArrayList<HashMap<String, String>> eventData;
78ListView finderListview;
79
80@Override
81protected void onCreate(Bundle savedInstanceState) {
82    super.onCreate(savedInstanceState);
83    setContentView(R.layout.activity_listview_finder_universities);
84
85
86     myDB = new UniversityFinderDB(this);
87
88    finderListview = (ListView) findViewById(R.id.finderListView);
89
90
91    myDB.executeEventInsert("UCI","101");
92
93    myDB.executeEventInsert("UeI","100");
94
95    myDB.executeEventInsert("UgI","105");
96
97    myDB.executeEventInsert("UjI","107");
98
99    myDB.executeEventInsert("ewI","109");
100
101    loadUnivFromDb();
102
103}
104
105private void createUnivAdapter(){
106    String from[]={"univId","univName"};
107    int to[] = {R.id.eventId, R.id.evenLabel};
108    SimpleAdapter adapter = new SimpleAdapter(getApplicationContext(), eventData, R.layout.uni_item_finder, from, to);
109    finderListview.setAdapter(adapter);
110}
111
112private void loadUnivFromDb() {
113    int gre = getIntent().getIntExtra("Gre",0);
114
115    ArrayList<HashMap<String, String>> data= myDB.executeSelectEvents(gre);
116    if(data.size()>0){
117        eventData=data;
118        createUnivAdapter();
119    }else {
120        Toast.makeText(getApplicationContext(),"NoEvents",Toast.LENGTH_SHORT).show();
121    }
122
123}
124
125
126}
127	
128public void executeEventInsert(String name, String score){
129     //For write data to your database
130     SQLiteDatabase db = this.getWritableDatabase();
131    String query="INSERT INTO universityFinder(univName, score) VALUES('"+name+"','"+score+"');";
132    db.execSQL(query);
133}
134	
135public ArrayList<HashMap<String,String>> executeSelectEvents(int input){
136    String query="select * from "+TABLE_NAME+ " where " +COLUMN_SCORE+" >="+input;
137    SQLiteDatabase db = this.getReadableDatabase();
138    Cursor cursor= db.rawQuery(query,null);
139    ArrayList<HashMap<String,String>> events=new ArrayList<>();
140    while (cursor.moveToNext()){
141        HashMap<String,String> event=new HashMap<>();
142
143        String colUniversityId=cursor.getColumnName(0);
144        String colUniversityIdValue=cursor.getString(0);
145        String colUniversityName=cursor.getColumnName(1);
146        String colUniversityValue=cursor.getString(1);
147
148
149        event.put(colUniversityId,colUniversityIdValue);
150        event.put(colUniversityName,colUniversityValue);
151        events.add(event);
152    }
153    return events;
154}