First I wanted the user to login and once login it wont go back to login screen until logout. So i added sharedPrefs. I was able to play around login>mainActivity then exit the app and open the app it would open mainActivity instead of login screen. Next I would logout and it would go back to login screen. As soon as I am in login screen I would exit the app and reopen the icon app and it would give an error. Another thing is when logout into the login screen and i press cancel button it would also give an error. I must have messed up the stack around but couldn’t find the solution. I included the logcat below which shows the part where i could not login anymore.
Login.java
public class Login extends Activity {
//protected static final SharedPreferences settings = null;
private EditText etUsername;
private Button btnLogin;
private Button btnCancel;
private TextView lblResult;
private String username;
@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
//replaces the default 'Back' button action
if(keyCode==KeyEvent.KEYCODE_BACK)
{
this.startActivity(new Intent(Login.this,Login.class));
}
return true;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
SharedPreferences.Editor editor = prefs.edit();
editor.putString("username", username);
if(prefs.getString("username", null)!=null)
{Intent i = new Intent(getApplicationContext(), Customer.class);
startActivity(i);}
etUsername = (EditText)findViewById(R.id.username);
btnLogin = (Button)findViewById(R.id.login_button);
btnCancel = (Button)findViewById(R.id.cancel_button);
lblResult = (TextView)findViewById(R.id.result);
btnLogin.setOnClickListener(new OnClickListener() {
//@Override
public void onClick(View v) {
// Check Login
String username = etUsername.getText().toString();
if(username.equals("1111")){
lblResult.setText("Login successful.");
Intent i = new Intent(getApplicationContext(), Customer.class);
startActivity(i);
btnCancel.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// Close the application
finish();
Logout.java
public class LogoutActivity extends Activity {
private Button btnLogout;
private Button btnCancel;
private TextView lblResult;
private EditText code;
@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
//replaces the default 'Back' button action
if(keyCode==KeyEvent.KEYCODE_BACK)
{
this.startActivity(new Intent(LogoutActivity.this,Customer.class));
}
return true;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.logout);
code = (EditText)findViewById(R.id.codeout);
btnLogout = (Button) findViewById(R.id.submit);
btnCancel = (Button) findViewById(R.id.cancel);
lblResult = (TextView)findViewById(R.id.result);
btnLogout.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
String logout = code.getText().toString();
if (logout.equals("99")){
lblResult.setText("Logout successful");
SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
SharedPreferences.Editor editor = settings.edit();
editor.remove("username");
Intent i = new Intent(getApplicationContext(), Login.class);
startActivity(i);
finish();
} else {
lblResult.setText("Logout failed");
}}});
btnCancel.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(getApplicationContext(), Customer.class);
startActivity(i);
}
Manifest.xml
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".Login"
android:noHistory="true"
android:excludeFromRecents="true"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
.............
<activity android:name=".LogoutActivity"
android:noHistory="true"
android:excludeFromRecents="true"
android:label="Logout"></activity>
Customer.java
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
public class Customer extends ListActivity
{
@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
//replaces the default 'Back' button action
if(keyCode==KeyEvent.KEYCODE_BACK)
{
this.startActivity(new Intent(Customer.this,Customer.class));
}
return true;
}
TextView selection;
CustomerListItem[] items = {
new CustomerListItem("Start Trip", StartTripActivity.class),
new CustomerListItem("Clock in", ClockinActivity.class),
new CustomerListItem("Customer Svc", CustomerSvcActivity.class),
new CustomerListItem("Independent Inspection", InspectionActivity.class),
new CustomerListItem("Pick Up", PickUpActivity.class),
new CustomerListItem("Log Out", LogoutActivity.class)};
private TextView resultsTxt;
@Override
public void onCreate(Bundle icicle)
{
super.onCreate(icicle);
setContentView(R.layout.customer);
setListAdapter(new ArrayAdapter<CustomerListItem>(
this, android.R.layout.simple_list_item_1, items));
selection = (TextView) findViewById(R.id.selection);
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id)
{
super.onListItemClick(l, v, position, id);
final Intent intent = new Intent(this, items[position].getActivity());
startActivityForResult(intent, position);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent)
{
super.onActivityResult(requestCode, resultCode, intent);
if (resultCode == RESULT_OK)
{
switch (requestCode)
{
case 0:
// TODO: handle the return of the StartTripActivity
break;
case 1:
// TODO: handle the return of the ClockinActivity
break;
case 2:
// TODO: handle the return of the CustomerSvcActivity
case 3:
// TODO: handle the return of the InspectionActivity
break;
case 4:
// TODO: handle the return of the PickUpActivity
break;
case 5:
// TODO: handle the return of the LogoutActivity
break;
default:
break;
}
}
else if (resultCode == RESULT_CANCELED)
{
resultsTxt.setText("Canceled");
}
}
}
Logcat
06-02 07:01:16.981: DEBUG/dalvikvm(981): GC freed 4479 objects / 199288 bytes in 104ms
06-02 07:01:20.632: WARN/KeyCharacterMap(2878): Bad keycharmap - filesize=32
06-02 07:01:20.632: WARN/KeyCharacterMap(2878): Error loading keycharmap file '/system/usr/keychars/qtouch-touchscreen.kcm.bin'. hw.keyboards.0.devname='qtouch-touchscreen'
06-02 07:01:20.632: WARN/KeyCharacterMap(2878): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
06-02 07:01:25.362: DEBUG/DispatchService(946): Handled message = TIMED_SERVICE_UNMASK
06-02 07:01:26.281: INFO/ActivityManager(900): Starting activity: Intent { comp={com.merrill2/com.merrill2.Customer} }
06-02 07:01:26.621: DEBUG/dalvikvm(959): GC freed 1008 objects / 58176 bytes in 180ms
06-02 07:01:26.681: INFO/ActivityManager(900): Displayed activity com.errill2/.Customer: 399 ms
06-02 07:01:30.121: DEBUG/DispatchService(946): Handled message = TIMED_SERVICE_UNMASK
06-02 07:01:38.941: INFO/ActivityManager(900): Starting activity: Intent { comp={com.merrill2/com.merrill2.LogoutActivity} }
06-02 07:01:39.281: INFO/ActivityManager(900): Displayed activity com.merrill2/.LogoutActivity: 330 ms
06-02 07:01:43.071: INFO/ActivityManager(900): Starting activity: Intent { comp={com.merrill2/com.merrill2.Login} }
06-02 07:01:43.631: DEBUG/OpenSSLSessionImpl(900): Freeing OpenSSL session
06-02 07:01:43.640: DEBUG/dalvikvm(900): GC freed 23770 objects / 1125392 bytes in 299ms
06-02 07:01:43.681: INFO/ActivityManager(900): Displayed activity com.merrill2/.Login: 606 ms
06-02 07:01:45.601: INFO/ActivityManager(900): Starting activity: Intent { action=android.intent.action.MAIN categories={android.intent.category.HOME} flags=0x10200000 comp={com.android.launcher/com.android.launcher.Launcher} }
06-02 07:01:45.781: WARN/IInputConnectionWrapper(2878): showStatusIcon on inactive InputConnection
06-02 07:01:47.475: INFO/ActivityManager(900): Starting activity: Intent { action=android.intent.action.MAIN categories={android.intent.category.LAUNCHER} flags=0x10200000 comp={com.merrill2/com.merrill2.Login} }
06-02 07:01:47.501: DEBUG/AndroidRuntime(2878): Shutting down VM
06-02 07:01:47.501: WARN/dalvikvm(2878): threadid=3: thread exiting with uncaught exception (group=0x40013140)
06-02 07:01:47.501: ERROR/AndroidRuntime(2878): Uncaught handler: thread main exiting due to uncaught exception
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=5, result=0, data=null} to activity {com.merrill2/com.merrill2.Customer}: java.lang.NullPointerException
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at android.app.ActivityThread.deliverResults(ActivityThread.java:3026)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at android.app.ActivityThread.handleSendResult(ActivityThread.java:3068)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at android.app.ActivityThread.access$2300(ActivityThread.java:128)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1739)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at android.os.Handler.dispatchMessage(Handler.java:99)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at android.os.Looper.loop(Looper.java:123)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at android.app.ActivityThread.main(ActivityThread.java:3992)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at java.lang.reflect.Method.invokeNative(Native Method)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at java.lang.reflect.Method.invoke(Method.java:521)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at dalvik.system.NativeStart.main(Native Method)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): Caused by: java.lang.NullPointerException
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at com.merrill2.Customer.onActivityResult(Customer.java:90)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at android.app.Activity.dispatchActivityResult(Activity.java:3595)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): at android.app.ActivityThread.deliverResults(ActivityThread.java:3022)
06-02 07:01:47.521: ERROR/AndroidRuntime(2878): ... 11 more
06-02 07:01:47.531: INFO/Process(900): Sending signal. PID: 2878 SIG: 3
06-02 07:01:47.551: INFO/dalvikvm(2878): threadid=7: reacting to signal 3
06-02 07:01:47.571: INFO/dalvikvm(2878): Wrote stack trace to '/data/anr/traces.txt'
06-02 07:01:50.482: INFO/Process(2878): Sending signal. PID: 2878 SIG: 9
06-02 07:01:50.501: INFO/ActivityManager(900): Process com.merrill2 (pid 2878) has died.
06-02 07:01:50.501: INFO/WindowManager(900): WIN DEATH: Window{437941d8 com.merrill2/com.merrill2.Customer paused=false}
06-02 07:01:50.501: INFO/WindowManager(900): WIN DEATH: Window{43877980 com.merrill2/com.merrill2.Login paused=true}
06-02 07:01:50.561: WARN/InputManagerService(900): Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@435e6fe8
06-02 07:01:54.363: DEBUG/DispatchService(946): Handled message = TIMED_SERVICE_UNMASK
06-02 07:01:55.740: DEBUG/dalvikvm(1225): GC freed 315 objects / 13368 bytes in 90ms
Debug Logcat
06-02 07:57:53.868: INFO/ActivityManager(900): Starting activity: Intent { comp={com.merrill2/com.merrill2.LogoutActivity} }
06-02 07:57:54.228: INFO/ActivityManager(900): Displayed activity com.merrill2/.LogoutActivity: 360 ms
06-02 07:57:56.968: DEBUG/dalvikvm(959): GC freed 985 objects / 56696 bytes in 86ms
06-02 07:57:57.669: WARN/KeyCharacterMap(2895): Bad keycharmap - filesize=32
06-02 07:57:57.669: WARN/KeyCharacterMap(2895): Error loading keycharmap file '/system/usr/keychars/qtouch-touchscreen.kcm.bin'. hw.keyboards.0.devname='qtouch-touchscreen'
06-02 07:57:57.669: WARN/KeyCharacterMap(2895): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
06-02 07:57:58.628: INFO/ActivityManager(900): Starting activity: Intent { comp={com.merrill2/com.merrill2.Login} }
06-02 07:57:58.768: DEBUG/dalvikvm(2895): GC freed 1710 objects / 109536 bytes in 87ms
06-02 07:57:59.118: INFO/ActivityManager(900): Displayed activity com.merrill2/.Login: 493 ms
06-02 07:58:02.565: DEBUG/DispatchService(946): Handled message = TIMED_SERVICE_UNMASK
06-02 07:58:05.438: INFO/ActivityManager(900): Starting activity: Intent { action=android.intent.action.MAIN categories={android.intent.category.HOME} flags=0x10200000 comp={com.android.launcher/com.android.launcher.Launcher} }
06-02 07:58:05.668: WARN/IInputConnectionWrapper(2895): showStatusIcon on inactive InputConnection
06-02 07:58:06.568: INFO/ActivityManager(900): Starting activity: Intent { action=android.intent.action.MAIN categories={android.intent.category.LAUNCHER} flags=0x10200000 comp={com.merrill2/com.merrill2.Login} }
06-02 07:58:06.588: DEBUG/AndroidRuntime(2895): Shutting down VM
06-02 07:58:06.588: WARN/dalvikvm(2895): threadid=3: thread exiting with uncaught exception (group=0x40013140)
06-02 07:58:06.588: ERROR/AndroidRuntime(2895): Uncaught handler: thread main exiting due to uncaught exception
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=5, result=0, data=null} to activity {com.merrill2/com.merrill2.Customer}: java.lang.NullPointerException
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at android.app.ActivityThread.deliverResults(ActivityThread.java:3026)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at android.app.ActivityThread.handleSendResult(ActivityThread.java:3068)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at android.app.ActivityThread.access$2300(ActivityThread.java:128)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1739)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at android.os.Handler.dispatchMessage(Handler.java:99)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at android.os.Looper.loop(Looper.java:123)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at android.app.ActivityThread.main(ActivityThread.java:3992)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at java.lang.reflect.Method.invokeNative(Native Method)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at java.lang.reflect.Method.invoke(Method.java:521)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at dalvik.system.NativeStart.main(Native Method)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): Caused by: java.lang.NullPointerException
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at com.merrill2.Customer.onActivityResult(Customer.java:90)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at android.app.Activity.dispatchActivityResult(Activity.java:3595)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): at android.app.ActivityThread.deliverResults(ActivityThread.java:3022)
06-02 07:58:06.598: ERROR/AndroidRuntime(2895): ... 11 more
06-02 07:58:06.638: INFO/Process(900): Sending signal. PID: 2895 SIG: 3
06-02 07:58:06.638: INFO/dalvikvm(2895): threadid=7: reacting to signal 3
06-02 07:58:06.668: INFO/dalvikvm(2895): Wrote stack trace to '/data/anr/traces.txt'
06-02 07:58:08.600: INFO/Process(2895): Sending signal. PID: 2895 SIG: 9
06-02 07:58:08.618: INFO/ActivityManager(900): Process com.merrill2 (pid 2895) has died.
06-02 07:58:08.628: INFO/WindowManager(900): WIN DEATH: Window{43748a70 com.merrill2/com.merrill2.Customer paused=false}
06-02 07:58:08.638: INFO/ActivityManager(900): Start proc com.merrill2 for activity com.merrill2/.Customer: pid=2932 uid=10053 gids={1006, 3003}
06-02 07:58:08.698: INFO/jdwp(2932): received file descriptor 10 from ADB
06-02 07:58:08.718: WARN/System.err(2932): Can't dispatch DDM chunk 46454154: no handler defined
06-02 07:58:08.728: WARN/System.err(2932): Can't dispatch DDM chunk 4d505251: no handler defined
06-02 07:58:08.918: DEBUG/dalvikvm(900): threadid=13: bogus mon 1+0>0; adjusting
06-02 07:58:08.918: DEBUG/dalvikvm(900): GC freed 24573 objects / 1334712 bytes in 275ms
06-02 07:58:08.938: INFO/WindowManager(900): WIN DEATH: Window{4368b128 com.merrill2/com.merrill2.Login paused=true}
06-02 07:58:09.178: DEBUG/AndroidRuntime(2932): Shutting down VM
06-02 07:58:09.178: WARN/dalvikvm(2932): threadid=3: thread exiting with uncaught exception (group=0x40013140)
06-02 07:58:09.178: ERROR/AndroidRuntime(2932): Uncaught handler: thread main exiting due to uncaught exception
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): java.lang.RuntimeException: Unable to resume activity {com.merrill2/com.merrill2.Customer}: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=5, result=0, data=null} to activity {com.merrill2/com.merrill2.Customer}: java.lang.NullPointerException
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2653)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2668)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2308)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.ActivityThread.access$1800(ActivityThread.java:128)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1710)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.os.Handler.dispatchMessage(Handler.java:99)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.os.Looper.loop(Looper.java:123)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.ActivityThread.main(ActivityThread.java:3992)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at java.lang.reflect.Method.invokeNative(Native Method)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at java.lang.reflect.Method.invoke(Method.java:521)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at dalvik.system.NativeStart.main(Native Method)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): Caused by: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=5, result=0, data=null} to activity {com.merrill2/com.merrill2.Customer}: java.lang.NullPointerException
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.ActivityThread.deliverResults(ActivityThread.java:3026)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2637)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): ... 12 more
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): Caused by: java.lang.NullPointerException
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at com.merrill2.Customer.onActivityResult(Customer.java:90)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.Activity.dispatchActivityResult(Activity.java:3595)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): at android.app.ActivityThread.deliverResults(ActivityThread.java:3022)
06-02 07:58:09.188: ERROR/AndroidRuntime(2932): ... 13 more
06-02 07:58:09.228: INFO/Process(900): Sending signal. PID: 2932 SIG: 3
06-02 07:58:09.228: INFO/dalvikvm(2932): threadid=7: reacting to signal 3
06-02 07:58:09.248: INFO/dalvikvm(2932): Wrote stack trace to '/data/anr/traces.txt'
06-02 07:58:12.538: DEBUG/DispatchService(946): Handled message = TIMED_SERVICE_UNMASK
06-02 07:58:16.577: WARN/ActivityManager(900): Launch timeout has expired, giving up wake lock!
06-02 07:58:18.971: WARN/ActivityManager(900): Activity idle timeout for HistoryRecord{43610e18 {com.merrill2/com.merrill2.Customer}}
06-02 07:58:24.058: DEBUG/dalvikvm(1225): GC freed 270 objects / 10200 bytes in 90ms
06-02 07:58:29.088: DEBUG/dalvikvm(981): GC freed 688 objects / 28808 bytes in 112ms
06-02 07:59:01.598: DEBUG/PowerManagerService(900): setPowerState: mPowerState=3 newState=1 noChangeLights=false
So your problem is resultsTxt, As you are not initialising it and trying to call .setText method on it. Try to initialise and check does everything work as you want.
how to :
Happy Coding!