Defining functions, variables, and events

Defining public functions, variables, and events that can be used from App Inventor.

Function that returns nothing

@SimpleFunction(description = "Does a thing")
public void FunctionWithoutReturn() {
    // Code to execute here
}

Function that returns a value

@SimpleFunction(description = "Does a thing and returns a result")
public Object FunctionWithReturn() {
    // Code to execute here
    return whateverYouWantToHaveAsAReturnValue;
}

Normal variable

private Object someVariableValue;
@DesignerProperty
@SimpleProperty(description="Gets the value")
public Object someVariable(){
    return someVariableValue;
}
@DesignerProperty
@SimpleProperty(description="Sets the value")
public void someVariable(Object newValue){
    someVariableValue = newValue;
}

Variable only settable from designer

private Object someVariableValue;
@DesignerProperty
@SimpleProperty(description="Gets the value")
public Object someVariable(){
    return someVariableValue;
}
@DesignerProperty()
public void someVariable(Object newValue){
    someVariableValue = newValue;
}

Variable only accessible from code

private Object someVariableValue;
@SimpleProperty(description="Gets the value")
public Object someVariable(){
    return someVariableValue;
}
@SimpleProperty(description="Sets the value")
public void someVariable(Object newValue){
    someVariableValue = newValue;
}