How to modify a List value while debugging in IntelliJ

13

I need to change a variable during debugging an application. Until now it was just basic variables which could directly be set. Now I need to clear an array so that isEmpty() returns true;

ArrayList<String> someList = new ArrayList<String>;

someList.add("1");

...

if(someList.isEmpty()){ //break point

//need to enter here

}

In the intellij debugger I see:

someList={ArrayList@4271} size=1

I used the 'setValue' method of the debugger and tried: new ArrayList<String>() or someList = new ArrayList<String>()

which results in

someList={ArrayList@4339} size=0

However if I continue I get a NullPointerException when the isEmpty() is called. So my question: How can I inject an empty ArrayList without getting a NPE?

The text of the NPe is: java.lang.NullPointerException: Attempt to invoke interface method 'boolean java.util.List.isEmpty()' on a null object reference

debugging android-studio intellij-idea intellij-14 android-studio-2.0

share|improve this question

asked Apr 20 '16 at 13:30

LonzakLonzak

4,92523158

add a comment | 

13

I need to change a variable during debugging an application. Until now it was just basic variables which could directly be set. Now I need to clear an array so that isEmpty() returns true;

ArrayList<String> someList = new ArrayList<String>;

someList.add("1");

...

if(someList.isEmpty()){ //break point

//need to enter here

}

In the intellij debugger I see:

someList={ArrayList@4271} size=1

I used the 'setValue' method of the debugger and tried: new ArrayList<String>() or someList = new ArrayList<String>()

which results in

someList={ArrayList@4339} size=0

However if I continue I get a NullPointerException when the isEmpty() is called. So my question: How can I inject an empty ArrayList without getting a NPE?

The text of the NPe is: java.lang.NullPointerException: Attempt to invoke interface method 'boolean java.util.List.isEmpty()' on a null object reference

debugging android-studio intellij-idea intellij-14 android-studio-2.0

share|improve this question

asked Apr 20 '16 at 13:30

LonzakLonzak

4,92523158

add a comment | 

13

13

13

2

I need to change a variable during debugging an application. Until now it was just basic variables which could directly be set. Now I need to clear an array so that isEmpty() returns true;

ArrayList<String> someList = new ArrayList<String>;

someList.add("1");

...

if(someList.isEmpty()){ //break point

//need to enter here

}

In the intellij debugger I see:

someList={ArrayList@4271} size=1

I used the 'setValue' method of the debugger and tried: new ArrayList<String>() or someList = new ArrayList<String>()

which results in

someList={ArrayList@4339} size=0

However if I continue I get a NullPointerException when the isEmpty() is called. So my question: How can I inject an empty ArrayList without getting a NPE?

The text of the NPe is: java.lang.NullPointerException: Attempt to invoke interface method 'boolean java.util.List.isEmpty()' on a null object reference

debugging android-studio intellij-idea intellij-14 android-studio-2.0

share|improve this question

asked Apr 20 '16 at 13:30

LonzakLonzak

4,92523158

I need to change a variable during debugging an application. Until now it was just basic variables which could directly be set. Now I need to clear an array so that isEmpty() returns true;

ArrayList<String> someList = new ArrayList<String>;

someList.add("1");

...

if(someList.isEmpty()){ //break point

//need to enter here

}

In the intellij debugger I see:

someList={ArrayList@4271} size=1

I used the 'setValue' method of the debugger and tried: new ArrayList<String>() or someList = new ArrayList<String>()

which results in

someList={ArrayList@4339} size=0

However if I continue I get a NullPointerException when the isEmpty() is called. So my question: How can I inject an empty ArrayList without getting a NPE?

The text of the NPe is: java.lang.NullPointerException: Attempt to invoke interface method 'boolean java.util.List.isEmpty()' on a null object reference

debugging android-studio intellij-idea intellij-14 android-studio-2.0

debugging android-studio intellij-idea intellij-14 android-studio-2.0

share|improve this question

asked Apr 20 '16 at 13:30

LonzakLonzak

4,92523158

share|improve this question

asked Apr 20 '16 at 13:30

LonzakLonzak

4,92523158

share|improve this question

share|improve this question

asked Apr 20 '16 at 13:30

LonzakLonzak

4,92523158

asked Apr 20 '16 at 13:30

LonzakLonzak

4,92523158

asked Apr 20 '16 at 13:30

LonzakLonzak

4,92523158

4,92523158

add a comment | 

add a comment | 

3 Answers
3

active

oldest

votes

14

Did you try to use the "Evaluate expression" during debug ("Alt + F8" on Windows) ?

In this window you can write :

 someList.clear();

or

someList = new ArrayList<String>();

And it should do the trick.

share|improve this answer

edited Apr 20 '16 at 13:43

Lonzak

4,92523158

answered Apr 20 '16 at 13:34

Guillaume MGuillaume M

220311

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick
  
  – Lonzak
  Apr 20 '16 at 13:42
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Oh Man, I was searching for this everywhere, finally found it thanks a lot for answering :)
  
  – Sudhanshu Gaur
  Dec 3 '18 at 20:27
  

  
  
  
  

add a comment | 

5

Stop the breakpoint at if(someList.isEmpty()), press ALT + F8 (evaluate expression), type someList.clear(), press Evaluate and just proceed on debugging. Now it will definitly enter the if condition.

share|improve this answer

answered Apr 20 '16 at 13:36

dambrosdambros

2,5281928

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick - your answer is correct. Guillaume was a bit faster so I accepted his answer - can't accept both ;-)
  
  – Lonzak
  Apr 20 '16 at 13:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  No problem. Glad to be able to help.
  
  – dambros
  Apr 20 '16 at 13:49
  

  
  
  
  

add a comment | 

0

I have this issue, but I am using Kotlin,
which you can do (someList as ArrayList<*>).clear()

share|improve this answer

answered Nov 20 '18 at 20:22

XianweiXianwei

384412

add a comment | 

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3 Answers
3

active

oldest

votes

3 Answers
3

active

oldest

votes

active

oldest

votes

active

oldest

votes

14

Did you try to use the "Evaluate expression" during debug ("Alt + F8" on Windows) ?

In this window you can write :

 someList.clear();

or

someList = new ArrayList<String>();

And it should do the trick.

share|improve this answer

edited Apr 20 '16 at 13:43

Lonzak

4,92523158

answered Apr 20 '16 at 13:34

Guillaume MGuillaume M

220311

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick
  
  – Lonzak
  Apr 20 '16 at 13:42
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Oh Man, I was searching for this everywhere, finally found it thanks a lot for answering :)
  
  – Sudhanshu Gaur
  Dec 3 '18 at 20:27
  

  
  
  
  

add a comment | 

14

Did you try to use the "Evaluate expression" during debug ("Alt + F8" on Windows) ?

In this window you can write :

 someList.clear();

or

someList = new ArrayList<String>();

And it should do the trick.

share|improve this answer

edited Apr 20 '16 at 13:43

Lonzak

4,92523158

answered Apr 20 '16 at 13:34

Guillaume MGuillaume M

220311

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick
  
  – Lonzak
  Apr 20 '16 at 13:42
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Oh Man, I was searching for this everywhere, finally found it thanks a lot for answering :)
  
  – Sudhanshu Gaur
  Dec 3 '18 at 20:27
  

  
  
  
  

add a comment | 

14

14

14

Did you try to use the "Evaluate expression" during debug ("Alt + F8" on Windows) ?

In this window you can write :

 someList.clear();

or

someList = new ArrayList<String>();

And it should do the trick.

share|improve this answer

edited Apr 20 '16 at 13:43

Lonzak

4,92523158

answered Apr 20 '16 at 13:34

Guillaume MGuillaume M

220311

Did you try to use the "Evaluate expression" during debug ("Alt + F8" on Windows) ?

In this window you can write :

 someList.clear();

or

someList = new ArrayList<String>();

And it should do the trick.

share|improve this answer

edited Apr 20 '16 at 13:43

Lonzak

4,92523158

answered Apr 20 '16 at 13:34

Guillaume MGuillaume M

220311

share|improve this answer

share|improve this answer

edited Apr 20 '16 at 13:43

Lonzak

4,92523158

edited Apr 20 '16 at 13:43

Lonzak

4,92523158

edited Apr 20 '16 at 13:43

Lonzak

4,92523158

4,92523158

answered Apr 20 '16 at 13:34

Guillaume MGuillaume M

220311

answered Apr 20 '16 at 13:34

Guillaume MGuillaume M

220311

answered Apr 20 '16 at 13:34

Guillaume MGuillaume M

220311

220311

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick
  
  – Lonzak
  Apr 20 '16 at 13:42
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Oh Man, I was searching for this everywhere, finally found it thanks a lot for answering :)
  
  – Sudhanshu Gaur
  Dec 3 '18 at 20:27
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick
  
  – Lonzak
  Apr 20 '16 at 13:42
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Oh Man, I was searching for this everywhere, finally found it thanks a lot for answering :)
  
  – Sudhanshu Gaur
  Dec 3 '18 at 20:27
  

  
  
  
  

thanks, yeah that did the trick

– Lonzak
Apr 20 '16 at 13:42

thanks, yeah that did the trick

– Lonzak
Apr 20 '16 at 13:42

Oh Man, I was searching for this everywhere, finally found it thanks a lot for answering :)

– Sudhanshu Gaur
Dec 3 '18 at 20:27

Oh Man, I was searching for this everywhere, finally found it thanks a lot for answering :)

– Sudhanshu Gaur
Dec 3 '18 at 20:27

add a comment | 

5

Stop the breakpoint at if(someList.isEmpty()), press ALT + F8 (evaluate expression), type someList.clear(), press Evaluate and just proceed on debugging. Now it will definitly enter the if condition.

share|improve this answer

answered Apr 20 '16 at 13:36

dambrosdambros

2,5281928

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick - your answer is correct. Guillaume was a bit faster so I accepted his answer - can't accept both ;-)
  
  – Lonzak
  Apr 20 '16 at 13:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  No problem. Glad to be able to help.
  
  – dambros
  Apr 20 '16 at 13:49
  

  
  
  
  

add a comment | 

5

Stop the breakpoint at if(someList.isEmpty()), press ALT + F8 (evaluate expression), type someList.clear(), press Evaluate and just proceed on debugging. Now it will definitly enter the if condition.

share|improve this answer

answered Apr 20 '16 at 13:36

dambrosdambros

2,5281928

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick - your answer is correct. Guillaume was a bit faster so I accepted his answer - can't accept both ;-)
  
  – Lonzak
  Apr 20 '16 at 13:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  No problem. Glad to be able to help.
  
  – dambros
  Apr 20 '16 at 13:49
  

  
  
  
  

add a comment | 

5

5

5

Stop the breakpoint at if(someList.isEmpty()), press ALT + F8 (evaluate expression), type someList.clear(), press Evaluate and just proceed on debugging. Now it will definitly enter the if condition.

share|improve this answer

answered Apr 20 '16 at 13:36

dambrosdambros

2,5281928

Stop the breakpoint at if(someList.isEmpty()), press ALT + F8 (evaluate expression), type someList.clear(), press Evaluate and just proceed on debugging. Now it will definitly enter the if condition.

share|improve this answer

answered Apr 20 '16 at 13:36

dambrosdambros

2,5281928

share|improve this answer

share|improve this answer

answered Apr 20 '16 at 13:36

dambrosdambros

2,5281928

answered Apr 20 '16 at 13:36

dambrosdambros

2,5281928

answered Apr 20 '16 at 13:36

dambrosdambros

2,5281928

2,5281928

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick - your answer is correct. Guillaume was a bit faster so I accepted his answer - can't accept both ;-)
  
  – Lonzak
  Apr 20 '16 at 13:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  No problem. Glad to be able to help.
  
  – dambros
  Apr 20 '16 at 13:49
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thanks, yeah that did the trick - your answer is correct. Guillaume was a bit faster so I accepted his answer - can't accept both ;-)
  
  – Lonzak
  Apr 20 '16 at 13:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  No problem. Glad to be able to help.
  
  – dambros
  Apr 20 '16 at 13:49
  

  
  
  
  

thanks, yeah that did the trick - your answer is correct. Guillaume was a bit faster so I accepted his answer - can't accept both ;-)

– Lonzak
Apr 20 '16 at 13:47

thanks, yeah that did the trick - your answer is correct. Guillaume was a bit faster so I accepted his answer - can't accept both ;-)

– Lonzak
Apr 20 '16 at 13:47

No problem. Glad to be able to help.

– dambros
Apr 20 '16 at 13:49

No problem. Glad to be able to help.

– dambros
Apr 20 '16 at 13:49

add a comment | 

0

I have this issue, but I am using Kotlin,
which you can do (someList as ArrayList<*>).clear()

share|improve this answer

answered Nov 20 '18 at 20:22

XianweiXianwei

384412

add a comment | 

0

I have this issue, but I am using Kotlin,
which you can do (someList as ArrayList<*>).clear()

share|improve this answer

answered Nov 20 '18 at 20:22

XianweiXianwei

384412

add a comment | 

0

0

0

I have this issue, but I am using Kotlin,
which you can do (someList as ArrayList<*>).clear()

share|improve this answer

answered Nov 20 '18 at 20:22

XianweiXianwei

384412

I have this issue, but I am using Kotlin,
which you can do (someList as ArrayList<*>).clear()

share|improve this answer

answered Nov 20 '18 at 20:22

XianweiXianwei

384412

share|improve this answer

share|improve this answer

answered Nov 20 '18 at 20:22

XianweiXianwei

384412

answered Nov 20 '18 at 20:22

XianweiXianwei

384412

answered Nov 20 '18 at 20:22

XianweiXianwei

384412

384412

add a comment | 

add a comment | 

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To learn more, see our tips on writing great answers.

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