added PTI calculation

app/src/main/java/com/sf/stormwaterutilityandroid/WaterWay/PTI.java

@@ -0,0 +1,39 @@
+package com.sf.stormwaterutilityandroid.WaterWay;
+
+public class PTI {
+    private double BM_intolerant = 0;
+    private double BM_moderately_tolerant = 0;
+    private double BM_fairly_tolerant = 0;
+    private double BM_very_tolerant = 0;
+
+    PTI(double BM_intolerant, double BM_moderately_tolerant, double BM_fairly_tolerant, double BM_very_tolerant) {
+        this.BM_intolerant = BM_intolerant;
+        this.BM_moderately_tolerant = BM_moderately_tolerant;
+        this.BM_fairly_tolerant = BM_fairly_tolerant;
+        this.BM_very_tolerant = BM_very_tolerant;
+    }
+
+    public void setBM_intolerant(double value) {
+        BM_intolerant = value;
+    }
+
+    public void setBM_moderately_tolerant(double value) {
+        BM_moderately_tolerant = value;
+    }
+
+    public void setBM_fairly_tolerant(double value) {
+        BM_fairly_tolerant = value;
+    }
+
+    public void setBM_very_tolerant(double value) {
+        BM_very_tolerant = value;
+    }
+
+    public double calculatePTI() {
+        return 4.0 * BM_intolerant + 3.0 * BM_moderately_tolerant + 2.0 * BM_fairly_tolerant + 1.0 * BM_very_tolerant;
+    }
+
+    public static double getPTI(double intolerant, double moderate, double fairly, double very) {
+        return 4.0 * intolerant + 3.0 * moderate + 2.0 * fairly + 1.0 * very;
+    }
+}