Add LASPoint.hasGPSTime()

src/main/java/com/github/mreutegg/laszip4j/LASPoint.java

@@ -141,10 +141,20 @@ public char getPointSourceID() {
         return p.getPoint_source_ID();
     }
 
+    /**
+     * @return {@code true} if this point has "GPS Time"; {@code false} otherwise.
+     */
+    public boolean hasGPSTime() {
+        return p.haveGpsTime();
+    }
+
     /**
      * @return "GPS Time" as a double.
+     * @throws IllegalStateException when called on a point without GPS Time.
+     * @see #hasGPSTime()
      */
     public double getGPSTime() {
+        checkHasGPSTime();
         return p.getGps_time();
     }
 
@@ -237,4 +247,10 @@ private void checkHasRGB() throws IllegalStateException {
             throw new IllegalStateException("Point does not have RGB data");
         }
     }
+
+    private void checkHasGPSTime() throws IllegalStateException {
+        if (!hasGPSTime()) {
+            throw new IllegalStateException("Point does not have GPS Time");
+        }
+    }
 }

src/main/java/com/github/mreutegg/laszip4j/laszip/LASpoint.java

@@ -418,7 +418,7 @@ private IGpsTimeProvider getGpsTimeProvider()
     {
         for(PointDataRecord  r : PointRecords)
         {
-            if (null != r && r instanceof IGpsTimeProvider)
+            if (r instanceof IGpsTimeProvider)
                 return (IGpsTimeProvider)r;
         }
 

src/test/java/com/github/mreutegg/laszip4j/LASReaderTest.java

@@ -545,4 +545,20 @@ public void readPointWithoutRGB() {
             }
         }
     }
+
+    @Test
+    public void readPointWithoutGPSTime() {
+        // extraBytes test file does not have GPS Time
+        LASReader reader = new LASReader(files.extraBytes);
+
+        for (LASPoint p : reader.getPoints()) {
+            assertFalse(p.hasGPSTime());
+            try {
+                p.getGPSTime();
+                fail("LASPoint.getGPSTime() must throw IllegalStateException");
+            } catch (IllegalStateException e) {
+                // expected
+            }
+        }
+    }
 }