How Dialog Builder under the click event can jump to a new Activity? Seeking education

I enclose my code:
Builder builder = new AlertDialog.Builder (this.Context); / / create dialog
builder.setTitle (R.string.tip); / / set the dialog title
builder.setMessage (R.string.not_setting_current_region); / / Settings dialog information
/ * Set dialog confirmation button * /
builder.setPositiveButton (R.string.confirm, new DialogInterface.OnClickListener ()
{

@ Override
public void onClick (DialogInterface dialog, int which)
{

dialog.dismiss ();
Intent intent = new Intent (Activity_SSGJ.this, Activity_select_City.class);
startActivity (intent);

Log.i (YangJ, "you click on the OK!");

}
});

I do not understand is why this jump was unsuccessful, click OK to stop? Great God seeking education<-! Main posts under Banner (D4) -><-! Posts under the main text (D5) ->
Reply:
So write should be fine, ah, what's your problem?
Reply:
Intent intent = new Intent (Activity_SSGJ.this, Activity_select_City.class);
Activity_SSGJ.this.startActivity (intent);
Try this
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Error Log paste ~
Reply:

There is a null pointer exception.
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reference to the second floor yinke22222 reply:

Intent intent = new Intent (Activity_SSGJ.this, Activity_select_City.class);
Activity_SSGJ.this.startActivity (intent);
Try this

like this is not OK I do not know how to engage, you can jump button is placed inside this popup will not work
Reply:

 
Builder builder = new AlertDialog.Builder (this); / / create dialog 
builder.setTitle ("title"); / / Set the dialog title 
builder.setMessage ("test"); / / Settings dialog information 
/ * Set dialog confirmation button * / 
builder.setPositiveButton ("OK", new DialogInterface.OnClickListener () {

public void onClick (DialogInterface dialog, int which) {

dialog.dismiss (); 
Intent intent = new Intent (MainActivity.this, TwoActivity.class); 
MainActivity.this.startActivity (intent); 

} 
.}) Show (); 

I tried the normal jump ah. . .
Reply:
1, these two plus AlertDialog dialog = builder.create ();
dialog.show ();
Reply:
There is a list of files in your activity registered yet
Reply:

 public class MainActivity extends Activity {
private Button btn; 
@ Override 
public void onCreate (Bundle savedInstanceState) {
super.onCreate (savedInstanceState); 
setContentView (R.layout.activity_main); 
btn = (Button) findViewById (R.id.button1); 
btn.setOnClickListener (new OnClickListener () 
{

@ Override 
public void onClick (View arg0) 
{
AlertDialog.Builder builder = new Builder (MainActivity.this); 
builder.setMessage ("Confirm Exit right?"); 

builder.setTitle ("Tip"); 

builder.setPositiveButton ("Confirm", new DialogInterface.OnClickListener () {

@ Override 
public void onClick (DialogInterface dialog, int which) {
dialog.dismiss (); 

Intent intent = new Intent (MainActivity.this, MainActivity2.class); 
startActivity (intent); 
} 
}); 

builder.setNegativeButton ("Cancel", new DialogInterface.OnClickListener () {

@ Override 
public void onClick (DialogInterface dialog, int which) {
dialog.dismiss (); 
} 
}); 

builder.create () show ();. 
} 
}); 

} 

I wrote one, not being given ah
You refer to
Reply:
Builder builder = new AlertDialog.Builder (this.Context); / / create dialog
- "
Builder builder = new AlertDialog.Builder (this); / / create dialog
I do not know what your this.Context is combined with a test of children's shoes, 6th Floor, reckoned that the problem is
Reply:

reference to the 6th floor yinke22222 reply:

Java code 1234567891011121314Builder builder = new AlertDialog.Builder (this); / / create dialog builder.setTitle ("title? "); / / set dialog title builder.setMessage (" test "); / / Setup dialog box message / * Set the dialogue ......

my grass, and I built a project can be jump. Spicy next door
Reply:

reference to the 8th floor kaka520169 reply:

There is a list of files in your activity registered yet

registered estimated I have a problem code structure
Reply:
Get.
Reply:

reference to the 13th floor YangJ0720 reply:

get.

This is how you solve the landlord, I also encountered the same problem