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I know I could set a breakpoint at every line where my code changes the variable, but is there an option such as right-clicking a variable (to "Add to Watches") that would stop when a variable changes value?

I think C++ has this option. See this.

And Eclipse? See this.

Is this implemented in AS?

Community
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DSlomer64
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4 Answers4

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You can break on value changes of some variables in Android Studio 1.1.0.

Android Studio calls them 'Java Field Watchpoints'.

From the breakpoints windows, (Run -> "View breakpoints...") or Ctrl+Shift+F8, you can add "Java Field Watchpoints" from the plus in the top left corner, and then select your class and variable.

Hrym
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    After keying Ctrl+Shift+F8 and pressing `+`, you then have a choice of breakpoint type: (1) method, (2) field, or (3) exception breakpoint. Thanks, @Hrym. – DSlomer64 Jun 14 '15 at 17:33
  • any idea how to do the same for C++ class members? – CCJ Jan 14 '20 at 20:34
5

If the goal is simply to set a watchpoint where execution halts if a variable's value changes, there are two methods:

Pressing Ctrl-shift-F8 to set a watchpoint brings up this dialog:

enter image description here

That looks more powerful but it's confusing because it lacks the option I need; and there's an extra step: filling in the dialog box below:

enter image description here

Once you fill it in correctly, you get the same options for stopping execution as in the simpler method below:

  1. Define the variable on one line ending with a semicolon.
  2. Left-click in the area where you set a normal breakpoint and up pops a dialog box. enter image description here
  3. Choose options to suit your needs.

Any instance where the value of the variable prefDbExists changes, execution will pause as at any "normal" (unconditional) breakpoint. And that's all I needed when I asked the original question.

EDIT: Fully qualified class name is {package name}.{class name})

DSlomer64
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2

What you seek for is commonly known as "WatchPoint". You will find detailed answer and examples on the doc. page of JetBrains - IntelliJ - Idea which is the basis for Android Studio.

https://www.jetbrains.com/help/idea/2016.3/creating-field-watchpoints.html

For me this works perfectly !

Sold Out
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0

Add a Kotlin Field Watchpoint by clicking on the space next to the line number for the field declaration in Android Studio. Select Kotlin Field Watchpoint from the Set Breakpoint menu. You will now get a breakpoint whenever that value changes.

Heath Kornblum
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