Java – Error:java: invalid flag: -release

Most likely you have incorrect compiler options imported from Maven here:

Also check project and module bytecode (target) version settings outlined on the screenshot.

Other places where the source language level is configured:

• Project Structure | Project

• Project Structure | Modules (check every module) | Sources

Maven default language level is 1.5 (5.0), you will see this version as the Module language level on the screenshot above.

This can be changed using maven-compiler-plugin configuration inside pom.xml:

<project>
  [...]
  <build>
    [...]
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
    [...]
  </build>
  [...]
</project>

or

<project>
  [...]
  <properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>
  [...]
</project>

IntelliJ IDEA will respect this setting after you Reimport the Maven project in the Maven Projects tool window:

Here is a try. The function is static and it may be used to check any class or object regardless of the class in which it is implemented. If you give it the type, it will use it, if you give it an instance, it will get the type by itself. The inner logic is just to check the given type description for the function we are looking for, if such exists and is declared by the class, it will check if the method also exists in the parent. And if both exists, enjoy, it means it is overridden.

/**
 * Returns true only if the method name given is declared by
 * the source class, and any parent class.
 */
static public function isOverridden(source:*, methodName:String):Boolean {
    var parentTypeName:String = getQualifiedSuperclassName(source);
    if (parentTypeName == null) {
        return false;
    }//if

    var typeName:String = getQualifiedClassName(source);
    var typeDesc:XML = describeType(getDefinitionByName(typeName));
    var methodList:XMLList = typeDesc.factory.method.(@name == methodName);

    if (methodList.length() > 0) {
        //Method exists
        var methodData:XML = methodList[0];
        if (methodData.@declaredBy == typeName) {
            //Method is declared in self
            var parentTypeDesc:XML = describeType(getDefinitionByName(parentTypeName));
            var parentMethodList:XMLList = parentTypeDesc.factory.method.(@name == methodName);
            return parentMethodList.length() > 0;
        }//if
    }//if

    return false;
}//isOverridden

And just in case it is needed, the imports required for it to work:

import flash.utils.describeType;
import flash.utils.getDefinitionByName;
import flash.utils.getQualifiedClassName;
import flash.utils.getQualifiedSuperclassName;

And to use it:

trace(isOverridden(ChildrenClass, "overriddenMethod")); //true
trace(isOverridden(ChildrenClass, "onlyChildMethod")); //false
trace(isOverridden(ChildrenClass, "onlyParentMethod")); //false