How to enable Intellij hot code swap

Question

Intellij does not seem to be doing basic hot code swap on my installation.

For this code:

public class MainTest {
    public void method1() {
                


        

Answer 1

After below modifications and enabling hot swap, a change in a Java file took 1-2 seconds of restart time. (Initial start time is around 7 seconds for me).

I hope below method helps...

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First, you need to check “Make project automatically” in preferences menu.

To open preferences menu;

you can go to top menu and click;

IntelliJ IDEA -> Preferences

or you can type below shortcut via keyboard;

cmd + option + s

Then, you can check Make project automatically as in below picture;

Secondly, you need to modify compiler.automake.allow.when.app.running registry setting as true.

To open registry, you need to click below keyboard shortcut:

cmd + shift + a

Type registry as in below picture, select Registry, and hit enter button of keyboard;

After Registry window opened, type compiler.automake to see compiler.automake.allow.when.app.running option, and check it as in below picture;

Then, you need to restart IntelliJ to make registry changes work.

Answer 2

I encountered this problem on Ubuntu. I also had an apparently unrelated issue where IntelliJ gave an error about the file watch limit (my apologies that I no longer have the exact error message). To solve this later issue I did the following steps:

1. Add the following line to either /etc/sysctl.conf file or a new *.conf file (e.g. idea.conf) under /etc/sysctl.d/ directory:

   fs.inotify.max_user_watches = 524288
   

2. Then run this command to apply the change:

   sudo sysctl -p --system

Now my React components rebuild and hot swap just fine.

Source

Answer 3

After saving your class while waiting on your breakpoint just recompile your class with Build -> Compile 'MainTest.java' or press Ctrl+Shift+F9 with the standard key bindings.

IntelliJ IDEA will then show a small dialog in which it asks you if you want to reload that class.

Answer 4

There is a Debugger > HotSwap option in intellij 11.

Answer 5

I think you are asking about this,

1. Right-click on your java class
2. Select Compile And Reload File

Answer 6

I wanted hotswap to automatically run every time I saved a Java file. None of the other answers did this so I just:

1. Created a macro that will run on save: https://stackoverflow.com/a/5581992/14731
2. Added Action: Hotswap at the end of the macro (Run -> Reload Changed Classes)