I am attempting to program the TSU9600 for a multi room installation. I would like to create a global variable for the selected room, for use in the volume control of an audio matrix system. I have tried declaring the global in the HOME properties -advanced tab as follows

var Room
System.setGlobal(Room) = 0 // Reset to Room to 0 every time home page is visited

I get errors when I try to set the global variable to other values, and when I try to reference this global.

I'm new to JAVA so would appreciate someone pointing out my errors.

System globals are named strings. As such the setGlobal function takes two arguments; the name for the string and the value of the string such as:

System.setGlobal("Room","0");

to retrieve the string use
x=System.getGlobal("Room"); which will set x as a string containing a 0

x=System.getGlobal("Room")-0; will force the conversion of the string to a number and set x as the integer 0

Hope that helps. Java, being without type declarations does most things as you would expect. The + operator however is overloaded and means addition or concatenation so a="1"; a=a+1; results in a being the string "11", while a="1"; a=a-0+1 results in a being the integer 2. This one burns me all the time as I deal with many languages and really prefer them to be strongly typed.

I just amended my code as you suggest, and it works!! Hurrah, I've been trying every combination possible, but would have never figured out how to convert the string to an integer. Many thanks for your swift and helpful reply.

The method I showed you is a "trick", but it always works.

Strings that are numeric can be "formally" converted to a number as stringname.toNumber e.g.
a="123"; x=a.toNumber will result in x being a number. Java holds numbers internally in floating point but that rarely causes a problem unless you are extracting bits. I use "JAVA Script, The Definitive Guide" by Flannagan as my reference. Easy to read, well laid out and explains with examples.

Number('123'); will convert to a number or the special value NaN (Not A Number). Also note that Javascript support both Positive and Negative infinity values. (See W3 schools for more info).

1/0 --> Positive Infinity
-1/0 --> Negative Infinity

Any text to numeric conversion that fails (Number() or parseInt())will return NaN and you can detect this with

isNaN(value)

var a=Number("123");
var b=parseInt('abc',10);
var c=parseInt('10',16);

System.print(a) --> 123
System.print(b) --> NaN
System.print(isNaN(b)) --> true
System.print(c) --> 16 ie. 10 in base 16(hexadecimal) is base 10 value of 16.

There's also a parseFloat function.