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testforstephen merged 3 commits into from
Oct 11, 2019
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Update troubleshooting doc for class not found error #685

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fd9c541
Update troubleshooting doc for class not found error
testforstephen Oct 11, 2019
b421c4e
Update hcr limitation
testforstephen Oct 11, 2019
1bfdc30
Address review comment
testforstephen Oct 11, 2019
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97 changes: 53 additions & 44 deletions Troubleshooting.md
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Expand Up @@ -10,42 +10,53 @@ The debugger works with [Language Support for Java(TM) by Red Hat](https://marke
### Try:
1. If you get the error *"The JAVA_HOME environment variable points to a missing folder"* or *"Java runtime could not be located"*, please make sure that the environment variable JAVA_HOME points to a valid JDK. Otherwise, ignore this step.
2. Open your Maven *pom.xml* file or Gradle *build.gradle* file, then run VS Code command *"Java: Update project configuration"* to force the language server to update the project configuration/classpath.
3. Try cleaning the stale workspace cache. Quit all VS Code processes and clean the following cache directory:
- Windows : %APPDATA%\Code\User\workspaceStorage\
- MacOS : $HOME/Library/Application Support/Code/User/workspaceStorage/
- Linux : $HOME/.config/Code/User/workspaceStorage/
3. Run VS Code command *"Java: Clean the Java language server workspace"* to clean the stale workspace cache.
4. Try more [troubleshooting guide](https://github.com/redhat-developer/vscode-java/wiki/Troubleshooting) from the language server product site.

## Failed to resolve classpath:
## Build failed, do you want to continue?
### Reason:
Below are the common failure reasons.
- 'C:\demo\org\microsoft\app\Main.java' is not a valid class name.
- Main class 'org.microsoft.app.Main' doesn't exist in the workspace.
- Main class 'org.microsoft.app.Main' isn't unique in the workspace.
- The project 'demo' is not a valid java project.
The error indicates your workspace has build errors. There are two kinds of build errors. One is compilation error for source code, the other is project error.

In launch mode, the debugger resolves the classpaths automatically based on the given `mainClass` and `projectName`. It looks for the class specified by `mainClass` as the entry point for launching an application. If there are multiple classes with the same name in the current workspace, the debugger uses the one inside the project specified by `projectName`.
### Try:
1. Open VS Code PROBLEMS View, and fix the errors there.
2. If no errors are found in the PROBLEMS View, reference the [language server troubleshooting](#try) paragraph to update project configuration, and clean workspace cache.

## x.java isn't on the classpath. Only syntax errors will be reported
### Reason:
This error indicates the Java file you opened isn't on the classpath of any project, and no .class file will be generated because Java language server only auto builds Java source files on the project classpath. If you try to run or debug this Java file, you may get the error "Could not find or load main class".

### Try:
1. Check whether the class name specified in `mainClass` exists and is in the right form. The debugger only works with fully qualified class names, e.g. `org.microsoft.app.Main`.
2. Check whether the `projectName` is correct. The actual project name is not always the same to the folder name you see in the File Explorer. Please check the value specified by `projectDescription/name` in the *.project* file, or the `artificatId` in the *pom.xml* for maven project, or the folder name for gradle project.
3. If the problem persists, please try to use the debugger to regenerate the debug configurations in *launch.json*. Remove the existing *launch.json* file and press F5. The debugger will automatically generate a new *launch.json* with the right debug configurations.
1. Go to *File Explorer*, right click the folder containing your Java file, and run the menu *"Add Folder to Java Source Path"* to mark the containing folder as a Java source root.
2. Run VS Code command *"Java: List all Java source paths"* to check whether the containing folder is added as a Java source root.

## Request type "xyz" is not supported. Only "launch" and "attach" are supported.
## Program Error: Could not find or load main class x
### Reason:
The value specified in `request` option of *launch.json* is incorrect.
You configure the incorrect main class name in `mainClass` of *launch.json*, or your Java file is not on the classpath.

### Try:
1. Reference the VS Code official document [launch configurations](https://code.visualstudio.com/docs/editor/debugging#_launch-configurations) about how to configure *launch.json*.
2. Try to use the debugger to regenerate the debug configurations in *launch.json*. Remove the existing *launch.json* file and press F5. The debugger will automatically generate a new *launch.json* with the right debug configurations.
1. Check whether the class name specified in `mainClass` exists and is in the right form.
2. Run VS Code command *"Java: List all Java source paths"* to show all source paths recognized by the workspace.
3. Check the Java file you are running is under any source path? If not, go to *File Explorer*, right click the folder containing your Java file, and run the menu *"Add Folder to Java Source Path"* to mark the containing folder as a Java source root.
4. Run VS Code command *"Java: Force Java compilation"* to rebuild your workspace.
5. If the problem persists, it's probably because the language server doesn't load your project correctly. Please reference the [language server troubleshooting](#try) paragraph for more troubleshooting info.

## Program throws ClassNotFoundException
### Reason:
This error indicates your application attempts to reference some classes which are not found in the entire classpaths.

### Try:
1. Check whether you configure the required libraries in the dependency settings file (e.g. *pom.xml*).
2. Run VS Code command *"Java: Force Java compilation"* to force the language server to rebuild the current project.
3. If the problem persists, it's probably because the language server doesn't load your project correctly. Please reference the [language server troubleshooting](#try) paragraph for more troubleshooting info.

## Failed to complete hot code replace:
### Reason:
This error indicates you are doing `Hot Code Replace`. The `Hot Code Replace` feature depends on the underlying JVM implementation. If you get this error, that indicates the new changes cannot be hot replaced by JVM.

### Try:
1. Restart your application to apply the new changes. Or ignore the message, and continue to debug.
2. You can disable the hot code replace feature by changing the user setting `"java.debug.settings.hotCodeReplace": "never"`.
1. Check the HCR limitation from the [wiki](https://github.com/microsoft/vscode-java-debug/wiki/Hot-Code-Replace).
2. Restart your application to apply the new changes. Or ignore the message, and continue to debug.
3. You can disable the hot code replace feature by changing the user setting `"java.debug.settings.hotCodeReplace": "never"`.

## Please specify the host name and the port of the remote debuggee in the launch.json.
### Reason:
Expand All @@ -65,43 +76,41 @@ There are two possible reasons for this error.
1. For Reason 1, try to add a breakpoint and stop your program there, then evaluate the expression.
2. For Reason 2, try to change the `console` option in the *launch.json* to `externalTerminal` or `integratedTerminal`. This is the official solution for program console input.

## The DEBUG CONSOLE throws Error: Could not find or load main class xyz
## Cannot find a class with the main method
### Reason:
You configure the incorrect main class name in `mainClass` of *launch.json*.
When the `mainClass` is unconfigured in the *launch.json*, the debugger will resolve a class with main method automatically. This error indicates the debugger doesn't find any main class in the whole workspace.

### Try:
1. Check whether the class name specified in `mainClass` exists and is in the right form.
2. If the problem persists, it's probably because the language server doesn't load your project correctly. Please reference the [language server troubleshooting](#try) paragraph for more troubleshooting info.
1. Check at least one main class exists in your workspace.
2. If no main class exists, please create a main class first. Otherwise, it's probably because the language server fails to start. Please reference the [language server troubleshooting](#try) paragraph for more troubleshooting info.

## The DEBUG CONSOLE throws ClassNotFoundException
## No delegateCommandHandler for vscode.java.startDebugSession when starting Debugger
### Reason:
This error indicates your application attempts to reference some classes which are not found in the entire classpaths.
Cause of error is for now unknown, but something caused vscode java support and debugger to not be configured correctly.

### Try:
1. Check whether you configure the required libraries in the dependency settings file (e.g. *pom.xml*).
2. Run VS Code command *"Java: Force Java compilation"* to force the language server to rebuild the current project.
3. If the problem persists, it's probably because the language server doesn't load your project correctly. Please reference the [language server troubleshooting](#try) paragraph for more troubleshooting info.
1. Restart VS Code and the issue should disappear
2. If it continues to error try restart again, and if still a problem open an issue at [vscode-java-debug](https://github.com/Microsoft/vscode-java-debug)

## Cannot find a class with the main method
## Failed to resolve classpath:
### Reason:
When the `mainClass` is unconfigured in the *launch.json*, the debugger will resolve a class with main method automatically. This error indicates the debugger doesn't find any main class in the whole workspace.

### Try:
1. Check at least one main class exists in your workspace.
2. If no main class exists, please create a main class first. Otherwise, it's probably because the language server fails to start. Please reference the [language server troubleshooting](#try) paragraph for more troubleshooting info.
Below are the common failure reasons.
- 'C:\demo\com\microsoft\app\Main.java' is not a valid class name.
- Main class 'com.microsoft.app.Main' doesn't exist in the workspace.
- Main class 'com.microsoft.app.Main' isn't unique in the workspace.
- The project 'demo' is not a valid java project.
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@jdneo jdneo Oct 11, 2019

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Is there anyway we can let the users know what is a valid java project?

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@testforstephen testforstephen Oct 11, 2019

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yes, the debugger will provide fix proposals quick pick for user to correct it if it finds the project is not valid.

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@jdneo jdneo Oct 11, 2019

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Upper case the word Java.


## Build failed, do you want to continue?
### Reason:
The error indicates your workspace has build errors. There are two kinds of build errors. One is compilation error for source code, the other is project error.
In launch mode, the debugger resolves the classpaths automatically based on the given `mainClass` and `projectName`. It looks for the class specified by `mainClass` as the entry point for launching an application. If there are multiple classes with the same name in the current workspace, the debugger uses the one inside the project specified by `projectName`.

### Try:
1. Open VS Code PROBLEMS View, and fix the errors there.
2. If no errors are found in the PROBLEMS View, reference the [language server troubleshooting](#try) paragraph to update project configuration, and clean workspace cache.
1. Check whether the class name specified in `mainClass` exists and is in the right form. The debugger only works with fully qualified class names, e.g. `com.microsoft.app.Main`.
2. Check whether the `projectName` is correct. The actual project name is not always the same to the folder name you see in the File Explorer. Please check the value specified by `projectDescription/name` in the *.project* file, or the `artificatId` in the *pom.xml* for maven project, or the folder name for gradle project.
3. If the problem persists, please try to use the debugger to regenerate the debug configurations in *launch.json*. Remove the existing *launch.json* file and press F5. The debugger will automatically generate a new *launch.json* with the right debug configurations.

## No delegateCommandHandler for vscode.java.startDebugSession when starting Debugger
## Request type "xyz" is not supported. Only "launch" and "attach" are supported.
### Reason:
Cause of error is for now unknown, but something caused vscode java support and debugger to not be configured correctly.
The value specified in `request` option of *launch.json* is incorrect.

### Try:
1. Restart VS Code and the issue should disappear
2. If it continues to error try restart again, and if still a problem open an issue at [vscode-java-debug](https://github.com/Microsoft/vscode-java-debug)
1. Reference the VS Code official document [launch configurations](https://code.visualstudio.com/docs/editor/debugging#_launch-configurations) about how to configure *launch.json*.
2. Try to use the debugger to regenerate the debug configurations in *launch.json*. Remove the existing *launch.json* file and press F5. The debugger will automatically generate a new *launch.json* with the right debug configurations.
2 changes: 0 additions & 2 deletions src/anchor.ts
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Expand Up @@ -5,7 +5,5 @@ export const REQUEST_TYPE_NOT_SUPPORTED = "request-type-xyz-is-not-supported-onl
export const FAILED_TO_COMPLETE_HCR = "failed-to-complete-hot-code-replace";
export const ATTACH_CONFIG_ERROR = "please-specify-the-host-name-and-the-port-of-the-remote-debuggee-in-the-launchjson";
export const EVALUATE_ON_RUNNING_THREAD = "failed-to-evaluate-reason-cannot-evaluate-because-the-thread-is-resumed";
export const DEBUGCONSOLE_MAIN_CLASS_NOT_FOUND = "the-debug-console-throws-error-could-not-find-or-load-main-class-xyz";
export const DEBUGCONSOLE_CLASS_NOT_FOUND_EXCEPTION = "the-debug-console-throws-classnotfoundexception";
export const CANNOT_FIND_MAIN_CLASS = "cannot-find-a-class-with-the-main-method";
export const BUILD_FAILED = "build-failed-do-you-want-to-continue";