update

Author: EvenSol

src/main/java/neqsim/thermodynamicoperations/BaseOperation.java

@@ -35,6 +35,13 @@ public double[] get(String name) {
     return new double[3];
   }
 
+  /** {@inheritDoc} */
+  @Override
+  public double[] get(String name, double[] defaultValue) {
+    double[] result = get(name);
+    return result != null ? result : defaultValue;
+  }
+
   /** {@inheritDoc} */
   @Override
   public String[][] getResultTable() {

src/main/java/neqsim/thermodynamicoperations/OperationInterface.java

@@ -72,6 +72,21 @@ public interface OperationInterface extends Runnable, java.io.Serializable {
    */
   public double[] get(String name);
 
+  /**
+   * Returns the named result array, or the supplied default if the key is not found or the result
+   * is {@code null}. This overload makes Python/JPype usage natural:
+   * {@code pe_data.get("dewT", emptyArray)} mirrors the Python dict {@code .get(key, default)}
+   * idiom.
+   *
+   * @param name the result key (e.g. "dewT", "bubP")
+   * @param defaultValue the array to return when the key is absent or maps to {@code null}
+   * @return the result array, or {@code defaultValue} if not found
+   */
+  default double[] get(String name, double[] defaultValue) {
+    double[] result = get(name);
+    return result != null ? result : defaultValue;
+  }
+
   /**
    * <p>
    * getJFreeChart.

src/main/java/neqsim/thermodynamicoperations/ThermodynamicOperations.java

@@ -2360,6 +2360,19 @@ public double[] get(String name) {
     return getOperation().get(name);
   }
 
+  /**
+   * Returns the named result array, or the supplied default if the key is not found or the result
+   * is {@code null}. Convenience for Python/JPype consumers where
+   * {@code ops.get("dewT", emptyArray)} mirrors the Python dict {@code .get(key, default)} idiom.
+   *
+   * @param name the result key (e.g. "dewT", "bubP")
+   * @param defaultValue the array to return when the key is absent or maps to {@code null}
+   * @return the result array, or {@code defaultValue} if not found
+   */
+  public double[] get(String name, double[] defaultValue) {
+    return getOperation().get(name, defaultValue);
+  }
+
   /**
    * <p>
    * Getter for the field <code>operation</code>.

src/test/java/neqsim/thermodynamicoperations/phaseenvelopeops/multicomponentenvelopeops/PTPhaseEnvelopeMichelsenTest.java

@@ -1,6 +1,7 @@
 package neqsim.thermodynamicoperations.phaseenvelopeops.multicomponentenvelopeops;
 
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
@@ -583,4 +584,54 @@ void testQualityLinesBubbleFirst() {
     assertTrue(qT25.length > 3, "Quality line 0.25 should have > 3 points");
     assertTrue(qT75.length > 3, "Quality line 0.75 should have > 3 points");
   }
+
+  /**
+   * Test that the get(String, double[]) overload returns results when the key exists and returns
+   * the default array when the key is absent or maps to null. This enables the Python/JPype idiom
+   * {@code pe_data.get("dewT", [])} that previously threw a JPype overload resolution error.
+   */
+  @Test
+  void testGetWithDefault() {
+    neqsim.thermo.system.SystemInterface testSystem =
+        new neqsim.thermo.system.SystemSrkEos(298.0, 50.0);
+    testSystem.addComponent("nitrogen", 0.01);
+    testSystem.addComponent("CO2", 0.01);
+    testSystem.addComponent("methane", 0.98);
+    testSystem.setMixingRule("classic");
+
+    ThermodynamicOperations testOps = new ThermodynamicOperations(testSystem);
+    testOps.TPflash();
+    testSystem.initProperties();
+    testOps.calcPTphaseEnvelope();
+
+    double[] emptyDefault = new double[0];
+
+    // Existing key should return actual data, not the default
+    double[] dewT = testOps.get("dewT", emptyDefault);
+    assertNotNull(dewT, "dewT with default should not be null");
+    assertTrue(dewT.length > 0, "dewT should have data points");
+    assertTrue(dewT != emptyDefault, "dewT should be the actual array, not the default");
+
+    double[] dewP = testOps.get("dewP", emptyDefault);
+    assertNotNull(dewP, "dewP with default should not be null");
+    assertTrue(dewP.length > 0, "dewP should have data points");
+
+    // Absent key should return the default
+    double[] unknown = testOps.get("nonExistentKey", emptyDefault);
+    assertArrayEquals(emptyDefault, unknown, "Absent key should return the default array");
+
+    // Key that maps to null (e.g. dewT2) should return the default
+    double[] dewT2 = testOps.get("dewT2", emptyDefault);
+    assertArrayEquals(emptyDefault, dewT2, "dewT2 (null) should return the default array");
+
+    // Also test via the OperationInterface directly
+    PTPhaseEnvelopeMichelsen env = (PTPhaseEnvelopeMichelsen) testOps.getOperation();
+    double[] bubP = env.get("bubP", emptyDefault);
+    assertNotNull(bubP, "bubP via operation with default should not be null");
+    assertTrue(bubP.length > 0, "bubP should have data points");
+
+    double[] missing = env.get("noSuchKey", emptyDefault);
+    assertArrayEquals(emptyDefault, missing,
+        "Absent key via operation should return the default array");
+  }
 }