Some things to keep in mind with when coding an indicator with multiple inputs & outputs.

1. Define correct number of arrays

I will need 2 time periods and 4 outputs, so first I have to make sure I start the arrays correctly:

private int[] timePeriod = new int[2];
private double[][] outputs = new double[4][];

2. Defining the correct parameter info for each item

I need to define 2 periods and 4 ouputs

indicatorInfo = new IndicatorInfo("maCross", "Moving Average Cross",
"My indicators",true, false, false, 1, 2, 4);

optInputParameterInfos = new OptInputParameterInfo[] {
   new OptInputParameterInfo("Time period 1:",
       OptInputParameterInfo.Type.OTHER,
       new IntegerRangeDescription(5, 2, 100, 1)),
   new OptInputParameterInfo("Time period 2:",
       OptInputParameterInfo.Type.OTHER,
       new IntegerRangeDescription(8, 2, 100, 1))
};

outputParameterInfos = new OutputParameterInfo[] {
   new OutputParameterInfo("MA1", OutputParameterInfo.Type.DOUBLE,
       OutputParameterInfo.DrawingStyle.LINE),
   new OutputParameterInfo("MA2", OutputParameterInfo.Type.DOUBLE,
       OutputParameterInfo.DrawingStyle.LINE),
   new OutputParameterInfo("UP", OutputParameterInfo.Type.DOUBLE,
       OutputParameterInfo.DrawingStyle.ARROW_SYMBOL_UP),
   new OutputParameterInfo("DOWN", OutputParameterInfo.Type.DOUBLE,
       OutputParameterInfo.DrawingStyle.ARROW_SYMBOL_DOWN)};

3. Calculating the Output Values

You need to use arrays for input values. In my case for the “time Period 1″ I have to use the first array value which is 0, and for the “time Period 2″ I use the second array value which is 1

outputs[0][j] = value/timePeriod[0];
outputs[1][j] = value2/timePeriod[1];
outputs[2][j] = 0;
outputs[3][j] = 0;

Also make sure you find values for all outputs. I have 4 outputs, so I need values for outputs[0], outputs[1], outputs[2] and outputs[3].

4. Download Sample Source code

Here is a sample source code for a maCross indicator I just coded for practice.

Click  to download: maCross.java