02-27 14:14:42.455: D/dalvikvm(1655): GC_FOR_ALLOC freed 46K, 5% free 2891K/3020K, paused 152ms, total 156ms
02-27 14:14:42.465: I/dalvikvm-heap(1655): Grow heap (frag case) to 3.668MB for 810016-byte allocation
02-27 14:14:42.545: D/dalvikvm(1655): GC_FOR_ALLOC freed 2K, 4% free 3680K/3812K, paused 76ms, total 77ms
02-27 14:14:43.425: I/Choreographer(1655): Skipped 35 frames! The application may be doing too much work on its main thread.
02-27 14:14:43.645: D/gralloc_goldfish(1655): Emulator without GPU emulation detected.
02-27 14:14:48.395: I/Choreographer(1655): Skipped 58 frames! The application may be doing too much work on its main thread.
02-27 14:14:49.725: I/Choreographer(1655): Skipped 58 frames! The application may be doing too much work on its main thread.
02-27 14:14:52.355: I/Choreographer(1655): Skipped 61 frames! The application may be doing too much work on its main thread.
02-27 14:14:55.195: D/AndroidRuntime(1655): Shutting down VM
02-27 14:14:55.195: W/dalvikvm(1655): threadid=1: thread exiting with uncaught exception (group=0xb3aaaba8)
02-27 14:14:55.275: E/AndroidRuntime(1655): FATAL EXCEPTION: main
02-27 14:14:55.275: E/AndroidRuntime(1655): Process: com.example.dreamhome, PID: 1655
02-27 14:14:55.275: E/AndroidRuntime(1655): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.dreamhome/com.example.dreamhome.LoginFormActivity}: java.lang.NullPointerException
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.app.ActivityThread.access$800(ActivityThread.java:135)
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.os.Handler.dispatchMessage(Handler.java:102)
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.os.Looper.loop(Looper.java:136)
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.app.ActivityThread.main(ActivityThread.java:5017)
02-27 14:14:55.275: E/AndroidRuntime(1655): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 14:14:55.275: E/AndroidRuntime(1655): at java.lang.reflect.Method.invoke(Method.java:515)
02-27 14:14:55.275: E/AndroidRuntime(1655): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
02-27 14:14:55.275: E/AndroidRuntime(1655): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
02-27 14:14:55.275: E/AndroidRuntime(1655): at dalvik.system.NativeStart.main(Native Method)
02-27 14:14:55.275: E/AndroidRuntime(1655): Caused by: java.lang.NullPointerException
02-27 14:14:55.275: E/AndroidRuntime(1655): at com.example.dreamhome.LoginFormActivity.onCreate(LoginFormActivity.java:45)
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.app.Activity.performCreate(Activity.java:5231)
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
02-27 14:14:55.275: E/AndroidRuntime(1655): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
02-27 14:14:55.275: E/AndroidRuntime(1655): ... 11 more
02-27 14:15:03.295: I/Process(1655): Sending signal. PID: 1655 SIG: 9
HomeActivity.java
public class HomeActivity extends Activity
{
Button search_property, log_in, exit;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
search_property=(Button)findViewById(R.id.homebutton1);
log_in=(Button)findViewById(R.id.homebutton2);
exit=(Button)findViewById(R.id.homebutton3);
search_property.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
Intent main1=new Intent(HomeActivity.this,EndUserSearchPropertyActivity.class);
startActivity(main1);
}
});
log_in.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
Intent main2 = new Intent(HomeActivity.this,LoginFormActivity.class);
startActivity(main2);
}
});
exit.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
finish();
System.exit(0);
}
});
// Show the Up button in the action bar.
setupActionBar();
}
/**
* Set up the {@link android.app.ActionBar}.
*/
private void setupActionBar()
{
getActionBar().setDisplayHomeAsUpEnabled(true);
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.home, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
case android.R.id.home:
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. Use NavUtils to allow users
// to navigate up one level in the application structure. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
这是 LoginFormActivity.java
public class LoginFormActivity extends Activity
{
private Button sign_up = null;
private Button btnSignIn = null;
LoginDataBaseAdapter loginDataBaseAdapter = null;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login_form);
// create a instance of SQLite Database
loginDataBaseAdapter=new LoginDataBaseAdapter(this);
loginDataBaseAdapter=loginDataBaseAdapter.open();
final Dialog dialog = new Dialog(LoginFormActivity.this);
// get the Refferences of views
final EditText editTextUserName=(EditText)dialog.findViewById(R.id.login_editText1);
final EditText editTextPassword=(EditText)dialog.findViewById(R.id.login_editText2);
btnSignIn = (Button)dialog.findViewById(R.id.login_form_button1);
// Set On ClickListener
btnSignIn.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
// get The User name and Password
String userName = editTextUserName.getText().toString();
String password = editTextPassword.getText().toString();
// fetch the Password form database for respective user name
String storedPassword=loginDataBaseAdapter.getSinlgeEntry(userName);
// check if the Stored password matches with Password entered by user
if(password.equals(storedPassword))
{
Toast.makeText(LoginFormActivity.this, "Congrats: Login Successfull", Toast.LENGTH_LONG).show();
dialog.dismiss();
}
else
{
Toast.makeText(LoginFormActivity.this, "User Name or Password does not match", Toast.LENGTH_LONG).show();
}
}
});
dialog.show();
}
@Override
protected void onDestroy()
{
super.onDestroy();
// Close The Database
loginDataBaseAdapter.close();
sign_up = (Button)findViewById(R.id.login_form_button2);
sign_up.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
Intent main2=new Intent(LoginFormActivity.this,SignupFormActivity.class);
startActivity(main2);
}
});
// Show the Up button in the action bar.
setupActionBar();
}
/**
* Set up the {@link android.app.ActionBar}.
*/
private void setupActionBar()
{
getActionBar().setDisplayHomeAsUpEnabled(true);
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.login_form, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
case android.R.id.home:
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. Use NavUtils to allow users
// to navigate up one level in the application structure. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
}
答案 0 :(得分：1)
final Dialog dialog = new Dialog(LoginFormActivity.this);
仅仅实例化dialog不会膨胀/创建其布局。所有后续的dialog.findViewById()调用都返回null，您将在此处获取NPE，尝试在空引用上调用方法：
btnSignIn = (Button)dialog.findViewById(R.id.login_form_button1);
// Set On ClickListener
btnSignIn.setOnClickListener(new View.OnClickListener()
您可能需要为包含要引用的所有视图的对话框设置内容视图。对话框显示后，findViewById()可以看到这些视图。