How to change Java GUI from Japanese to English
Article ID: 432058
Updated On:
Products
Network Observability
Issue/Introduction
How to change the OneClick Java GUI display language from Japanese to English on specific client PCs without affecting the entire server
Environment
24.x
25.x
Cause
Java on Windows reads the default locale from OS regional settings unless explicitly overridden by JVM flags
Resolution
Recommended Solution — Per-Client Approach
The customer's requirement is:
English UI on specific client PCs
Japanese UI on all other client PCs
This rules out server-side Tomcat JVM changes (which would affect all clients). Here are the approaches, from most practical to least:
Option 1: Set JVM Default Locale on the Client PC (Windows)
On the specific Windows client PCs where English is desired, set these Windows system environment variables:
JAVA_TOOL_OPTIONS=-Duser.language=en -Duser.country=US
This environment variable is honored by every JVM that starts on that machine, including the one launched by OneClick's JNLP/Web Start. Unlike LANG/LC_ALL, JAVA_TOOL_OPTIONS is a standard Java mechanism that works on Windows.
Steps:
Open System Properties > Advanced > Environment Variables
Under System variables, click New
Variable name: JAVA_TOOL_OPTIONS
Variable value: -Duser.language=en -Duser.country=US
Click OK, close all dialogs
Restart the OneClick client
When the JVM starts, you'll see a message like Picked up JAVA_TOOL_OPTIONS: -Duser.language=en -Duser.country=US — this confirms it took effect.
Pros: Per-client, no server changes, survives JNLP regeneration.
Cons: Affects all Java applications on that PC (usually not an issue).
Option 1: Set JVM Default Locale on the Client PC (Windows)
On the specific Windows client PCs where English is desired, set these Windows system environment variables:
JAVA_TOOL_OPTIONS=-Duser.language=en -Duser.country=US
This environment variable is honored by every JVM that starts on that machine, including the one launched by OneClick's JNLP/Web Start. Unlike LANG/LC_ALL, JAVA_TOOL_OPTIONS is a standard Java mechanism that works on Windows.
Steps:
Open System Properties > Advanced > Environment Variables
Under System variables, click New
Variable name: JAVA_TOOL_OPTIONS
Variable value: -Duser.language=en -Duser.country=US
Click OK, close all dialogs
Restart the OneClick client
When the JVM starts, you'll see a message like Picked up JAVA_TOOL_OPTIONS: -Duser.language=en -Duser.country=US — this confirms it took effect.
Pros: Per-client, no server changes, survives JNLP regeneration.
Cons: Affects all Java applications on that PC (usually not an issue).
Option 2: Use _JAVA_OPTIONS (Alternative)
Same approach but using _JAVA_OPTIONS instead:
_JAVA_OPTIONS=-Duser.language=en -Duser.country=US
This behaves identically to JAVA_TOOL_OPTIONS but takes precedence over it.
Same approach but using _JAVA_OPTIONS instead:
_JAVA_OPTIONS=-Duser.language=en -Duser.country=US
This behaves identically to JAVA_TOOL_OPTIONS but takes precedence over it.
Option 3: Change Windows Display Language (Per-User)
On the specific client PCs, change the Windows locale/region settings to English:
Settings > Time & Language > Language & Region
Set Windows display language to English (United States)
Under Region > Regional format, set to English (United States)
Restart the PC
Java on Windows reads the default locale from the OS regional settings. This would cause the OneClick JVM to start with en_US locale without any JVM flags.
Pros: Clean, no JVM flag hacking.
Cons: Changes the entire Windows UI language for that user, which may not be desired.
On the specific client PCs, change the Windows locale/region settings to English:
Settings > Time & Language > Language & Region
Set Windows display language to English (United States)
Under Region > Regional format, set to English (United States)
Restart the PC
Java on Windows reads the default locale from the OS regional settings. This would cause the OneClick JVM to start with en_US locale without any JVM flags.
Pros: Clean, no JVM flag hacking.
Cons: Changes the entire Windows UI language for that user, which may not be desired.
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