My android application closes when moving to another activity
Question
i'm new here and new to programming in general
I'm creating a blood donation android application with SQLite and when i move to another activity to display the donors it closes.
I created a database using DB Helper Here is the code:
public class BloodBankDatabaseHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "Bloodbank";
private static final int DB_VERSION = 1;
BloodBankDatabaseHelper (Context context){
super(context, "Bloodbank", null, 1 );
}
@Override
public void onCreate(SQLiteDatabase db){
db.execSQL("CREATE TABLE DONOR ("
+ "_id INTEGER PRIMARY KEY AUTOINCREMENT, "
+ "NAME TEXT,"
+ "BLOOD TEXT, "
+ "PHONE TEXT, " + " DISTRICT TEXT"
+ " EMAIL TEXT);");
insertDonor(db, "Bilal Achi", "O+", "03567773", "Beirut", "bilal.achi@hotmail.com");
insertDonor(db, "Mohamad", "O-", "03024026","Beirut", "Mohamad@hotmail.com");
insertDonor(db, "Fadi", "A-", "03444333","Beirut", "Fadi211@hotmail.com");
insertDonor(db, "Hadi", "B-", "03123122", "Beirut", "Hadi@hotmail.com");
insertDonor(db, "Rana", "AB+", "03974267", "Beirut", "Rana121@hotmail.com");
insertDonor(db, "Sara", "A+", "03123891", "Beirut", "Sarah@hotmail.com");
insertDonor(db, "Khalil", "B-", "03456189", "Beirut", "Khalil088@hotmail.com");
insertDonor(db, "Jad", "O-", "03999211", "Tyre", "Jad992@hotmail.com");
insertDonor(db, "Siham", "AB+", "03213477", "Tyre", "Siham1112@hotmail.com");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + "DONOR");
onCreate(db);
}
private static void insertDonor(SQLiteDatabase db, String name, String blood, String phone,
String disctrict, String email) {
ContentValues donorValues = new ContentValues();
donorValues.put("NAME",name);
donorValues.put("BLOOD", blood);
donorValues.put("PHONE", phone);
donorValues.put("Email", email);
donorValues.put("DISTRICT",disctrict);
db.insert("DONOR", null, donorValues );
}
}
My main activity consists of two spinner to specify the district and blood type and a button to move to the activity
Here is the Code for the main activity
public class MainActivity extends AppCompatActivity {
private SQLiteDatabase db;
private Spinner sp1;
private Spinner sp2;
private Button bt1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sp1 = (Spinner)findViewById(R.id.spnr1);
sp2 = (Spinner)findViewById(R.id.spnr2);
bt1 = (Button)findViewById(R.id.btnSearch);
String[] Districts = {"Aley ","Akkar ","Baabda ","Baalback ","Batroun ","Beirut ",
"Bsharri ","Chouf ","Hasbaya ","Hermel ","Jbeil ","Jizzine ","Keserwan ",
"Koura ", "Marjeyoun ","Matn ","Miniyeh-Danniyeh ","Nabatieh ","Rashaya ","Sydon ",
"Tripoli ","Tyre ","Western Bekaa ","Zahle ","Zgharta "};
String [] BloodTypes = {"O+ ", "O- ","A+ ","A- ","B+ ",
"B- ","AB+ ","AB- "};
ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this,R.layout.support_simple_spinner_dropdown_item, Districts);
sp1.setAdapter(adapter);
ArrayAdapter<String> adapter2 = new ArrayAdapter<String>(MainActivity.this,R.layout.support_simple_spinner_dropdown_item, BloodTypes);
sp2.setAdapter(adapter2);
sp1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String item = ((TextView)view).getText().toString();
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
sp2.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String item = ((TextView)view).getText().toString();
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
bt1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String Districts = sp1.getSelectedItem().toString();
String bloodtypes = sp2.getSelectedItem().toString();
Intent intent = new Intent(MainActivity.this, Donor.class);
startActivity(intent);
}
});
}
}
Now when the button is pressed a new activity should start displaying the donors but the application crashes Here is the code
public class Donor extends AppCompatActivity {
public static final String Extra_Disctrict = "Districts";
public static final String Extra_type = "bloodtypes";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_donor);
String Districts = (String)getIntent().getExtras().get(Extra_Disctrict);
String bloodtypes = (String)getIntent().getExtras().get(Extra_type);
//Create a Cursor
try {
SQLiteOpenHelper BloodBankDatabaseHelper = new BloodBankDatabaseHelper(this);
SQLiteDatabase db = BloodBankDatabaseHelper.getReadableDatabase();
Cursor cursor = db.query("Bloodbank",
new String[]{"NAME", "PHONE", "EMAIL"},
"DISTRICT = ? AND BLOOD = ?",
new String []{(Districts),(bloodtypes)}, null, null, null);
if (cursor.moveToFirst()) {
String nameText = cursor.getString(0);
String phoneText = cursor.getString(1);
String emailText = cursor.getString(2);
TextView name = (TextView)findViewById(R.id.name);
name.setText(nameText);
TextView phone = (TextView)findViewById(R.id.phone);
phone.setText(phoneText);
TextView email = (TextView)findViewById(R.id.email);
email.setText(emailText);
}
cursor.close();
db.close();
} catch(SQLiteException e) {
Toast toast = Toast.makeText(this, "Database unavailable", Toast.LENGTH_SHORT);
toast.show();
}
}
}
and here is the Logcat
01-19 00:10:03.491 3316-3316/? E/AndroidRuntime: in writeCrashedAppName, pkgName :com.example.bilal.bloodbank
01-19 00:10:03.521 3316-3316/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.bilal.bloodbank, PID: 3316
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.bilal.bloodbank/com.example.bilal.bloodbank.Donor}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
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:5021)
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:827)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.bilal.bloodbank.Donor.onCreate(Donor.java:24)
at android.app.Activity.performCreate(Activity.java:5397)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1090)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
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:5021)
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:827)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
at dalvik.system.NativeStart.main(Native Method)
01-19 00:10:04.171 4174-4174/? E/AndroidRuntime: in writeCrashedAppName, pkgName :com.example.bilal.bloodbank
01-19 00:10:04.201 4174-4174/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.bilal.bloodbank, PID: 4174
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.bilal.bloodbank/com.example.bilal.bloodbank.Donor}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
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:5021)
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:827)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.bilal.bloodbank.Donor.onCreate(Donor.java:24)
at android.app.Activity.performCreate(Activity.java:5397)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1090)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
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:5021)
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:827)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
at dalvik.system.NativeStart.main(Native Method)
01-19 00:10:04.741 4186-4186/? E/AndroidRuntime: in writeCrashedAppName, pkgName :com.example.bilal.bloodbank
01-19 00:10:04.761 4186-4186/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.bilal.bloodbank, PID: 4186
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.bilal.bloodbank/com.example.bilal.bloodbank.Donor}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
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:5021)
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:827)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.bilal.bloodbank.Donor.onCreate(Donor.java:24)
at android.app.Activity.performCreate(Activity.java:5397)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1090)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
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:5021)
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:827)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
at dalvik.system.NativeStart.main(Native Method)
01-19 00:10:11.361 1773-4205/system_process E/ActivityManager: Exception in bstSendTopActivityInfo while sending HttpPost: Connect to /10.0.2.2:2861 timed out
Your help would be highly Appreciated Thanks
1 answers
solution1
2 ACCPTED 2018-01-18 22:20:43
The important part of your LogCat entry is
Caused by: java.lang.NullPointerException at com.example.bilal.bloodbank.Donor.onCreate(Donor.java:24)
Line 24 of Donor.java
String Districts = (String)getIntent().getExtras().get(Extra_Disctrict);
is trying to get Districts out of the Intent extras Bundle but getExtras() is returning null. Your main activity code is not adding any extras to the intent:
String Districts = sp1.getSelectedItem().toString();
String bloodtypes = sp2.getSelectedItem().toString();
Intent intent = new Intent(MainActivity.this, Donor.class);
startActivity(intent);
Add your Strings to the intent extras before calling startActivity.
intent.putExtra("Districts", Districts);
intent.putExtra("bloodtypes", bloodtypes);
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