Java: Adding example for MQ3 Gas Sensor

Signed-off-by: Abhishek Malik <abhishek.malik@intel.com>

examples/java/GroveMQ3.java

@@ -0,0 +1,58 @@
+import upm_gas.Gas;
+import upm_gas.MQ2;
+import upm_gas.MQ3;
+import upm_gas.MQ4;
+import upm_gas.MQ5;
+import upm_gas.MQ6;
+import upm_gas.MQ7;
+import upm_gas.MQ8;
+import upm_gas.MQ9;
+import upm_gas.TP401;
+import upm_gas.thresholdContext;
+
+public class GroveMQ3 {
+
+	static {
+		try {
+			System.loadLibrary("javaupm_gas");
+			System.loadLibrary("mraajava");
+		} catch (UnsatisfiedLinkError e) {
+			System.err.println(
+					"Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.\n" +
+							e);
+			System.exit(1);
+		}
+	}
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		//! [Interesting]
+		// initialize the sensor on A0
+		MQ3 mq3 = new MQ3(0);
+
+		short[] buffer = new short[128];
+
+		thresholdContext context = new thresholdContext();
+
+		context.setAverageReading(0);
+		context.setRunningAverage(0);
+		context.setAveragedOver(2);
+
+		int len;
+		int thres;
+		while(true){
+			len = mq3.getSampledWindow((long)2, buffer);
+
+			if(len != 0){
+				thres = mq3.findThreshold(context, 30, buffer);
+				mq3.printGraph(context, (short)5);
+				if(thres != 0){
+					// do something
+					System.out.println("threshold is crossed");
+				}
+			}
+		}
+		//! [Interesting]
+	}
+
+}