Unreachable code
Reports the code which is never reached according to data flow analysis. It can be the result of previous always-true or always-false condition, unreachable loop body or catch section. Usually (though not always) unreachable code is a consequence of a previous warning, so check inspection warnings form "Nullability and data flow problems", "Constant values", or "Redundant operation on empty container" to better understand the cause.
Example:
void finishApplication() {
System.exit(0);
System.out.println("Application is terminated"); // Unreachable code
}
Note that this inspection relies on method contract inference. In particular, if you call a static or final method that always throws an exception, then the "always failing" contract will be inferred, and code after the method call will be considered unreachable. For example:
void run() {
performAction();
System.out.println("Action is performed"); // Unreachable code
}
static void performAction() {
throw new AssertionError();
}
This may cause false-positives if any kind of code postprocessing is used, for example, if an annotation processor later replaces the method body with something useful. To avoid false-positive warnings, suppress the automatic contract inference with explicit @org.jetbrains.annotations.Contract
annotation from org.jetbrains:annotations
package:
void run() {
performAction();
System.out.println("Action is performed"); // No warning anymore
}
@Contract("-> _") // implementation will be replaced
static void performAction() {
throw new AssertionError();
}
- By ID
Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.
-UnreachableCode
New in 2024.1
Here you can find the description of settings available for the Unreachable code inspection, and the reference of their default values.
Inspection Details | |
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By default bundled with: | |
Can be installed with plugin: | Java, 243.23126 |
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