javachk

R2026b

Error message based on Java feature support

Syntax

MSG = javachk(feature)

javachk(feature,component)

Description

MSG = javachk(feature) returns a generic error message if the specified Java^® feature is not available in the current MATLAB^® session.

javachk(feature,component) also names the specified component in the error message.

Examples

Generate Error If Java Not Available

To test if Java is available before calling a Java command, use these statements. The isempty function is true when there is no error.

if isempty(javachk("jvm"))
   scalar = java.lang.Double(5);
end

Input Arguments

feature — Java feature

"awt" | "desktop" | "jvm" | "swing"

Java feature, specified as one of these values.

"awt"	UI components in the Java Abstract Window Toolkit (AWT) are available. To be removed.
"desktop"	MATLAB interactive desktop is running. To be removed.
"jvm"	Java Virtual Machine software (JVM®) is available.
"swing"	Swing components (Java lightweight UI components in the Java Foundation Classes) are available. To be removed.

component — Identifier

string | character vector

Identifier, specified as a string or a character vector, to display in the error message.

Output Arguments

MSG — Error message

structure

Error message, returned as a structure with the following fields. If the feature is available, javachk returns an error structure with empty fields.

message — Message

character vector | empty

Message, specified as a character vector.

identifier — Identifier

character vector | empty

Identifier, specified as a character vector.

Version History

Introduced before R2006a

R2026b: "awt" and "swing" options will be removed

The "awt" and "swing" options for the feature argument will be removed in a future release.

To detect Java:

usejava("jvm")

To detect the desktop:

desktop("inuse")

R2025a: "desktop" option will be removed

The "desktop" option for the feature argument will be removed in a future release.