NullPointerException can be caused by calling ProxyObject#dispose mul…

…tiple times

Closes: java-native-access#894

CHANGES.md

@@ -18,6 +18,7 @@ Bug Fixes
 * [#876](https://github.com/java-native-access/jna/pull/876): Restore java 6 compatibility - [@matthiasblaesing](https://github.com/matthiasblaesing).
 * [#882](https://github.com/java-native-access/jna/pull/882): Correctly close file in `ELFAnalyser#runDetection`, fix suggested by [@Sylvyrfysh](https://github.com/Sylvyrfysh) in [#880](https://github.com/java-native-access/jna/pull/880) - [@matthiasblaesing](https://github.com/matthiasblaesing).
 * [#887](https://github.com/java-native-access/jna/issues/887): MacFileUtils.moveToTrash() doesn't work in a sandboxed app fix suggested by [@sobakasu](https://github.com/sobakasu) - [@matthiasblaesing](https://github.com/matthiasblaesing).
+* [#894](https://github.com/java-native-access/jna/issues/894): NullPointerException can be caused by calling `com.sun.jna.platform.win32.COM.util.ProxyObject#dispose` multiple times - [@matthiasblaesing](https://github.com/matthiasblaesing).
 
 Breaking Changes
 ----------------

contrib/platform/src/com/sun/jna/platform/win32/COM/util/ProxyObject.java

@@ -34,7 +34,6 @@
 import com.sun.jna.platform.win32.Guid;
 import com.sun.jna.platform.win32.Guid.IID;
 import com.sun.jna.platform.win32.Guid.REFIID;
-import com.sun.jna.platform.win32.Kernel32;
 import com.sun.jna.platform.win32.Kernel32Util;
 import com.sun.jna.platform.win32.OaIdl;
 import com.sun.jna.platform.win32.OaIdl.DISPID;
@@ -46,7 +45,6 @@
 import com.sun.jna.platform.win32.Variant.VARIANT;
 import com.sun.jna.platform.win32.WinDef;
 import com.sun.jna.platform.win32.WinDef.DWORDByReference;
-import com.sun.jna.platform.win32.WinDef.LCID;
 import com.sun.jna.platform.win32.WinNT;
 import com.sun.jna.platform.win32.WinNT.HRESULT;
 import com.sun.jna.platform.win32.COM.COMException;
@@ -134,7 +132,7 @@ protected void finalize() throws Throwable {
 	}
 
 	public synchronized void dispose() {
-		if (! ((Dispatch) this.rawDispatch).getPointer().equals(Pointer.NULL)) {
+		if (((Dispatch) this.rawDispatch).getPointer() != Pointer.NULL) {
 			this.rawDispatch.Release();
                         ((Dispatch) this.rawDispatch).setPointer(Pointer.NULL);
                         factory.unregister(this);

contrib/platform/test/com/sun/jna/platform/win32/COM/util/ProxyObjectFactory_Test.java

@@ -12,7 +12,6 @@
  */
 package com.sun.jna.platform.win32.COM.util;
 
-import com.sun.jna.Pointer;
 import static org.junit.Assert.*;
 
 import java.io.File;
@@ -25,7 +24,6 @@
 import com.sun.jna.platform.win32.COM.util.annotation.ComObject;
 import com.sun.jna.platform.win32.COM.util.annotation.ComMethod;
 import com.sun.jna.platform.win32.COM.util.annotation.ComProperty;
-import com.sun.jna.platform.win32.Ole32;
 
 public class ProxyObjectFactory_Test {
 

contrib/platform/test/com/sun/jna/platform/win32/COM/util/ProxyObjectObjectFactory_Test.java

@@ -15,6 +15,8 @@
 import com.sun.jna.Pointer;
 import static org.junit.Assert.*;
 
+import java.lang.reflect.Proxy;
+
 import java.io.File;
 
 import org.junit.After;
@@ -156,7 +158,8 @@ public void notEquals() {
 	@Test
 	public void accessWhilstDisposing() {
 		MsWordApp comObj1 = this.factory.createObject(MsWordApp.class);
-
+		comObj1.Quit();
+
 		//TODO: how to test this?
 
 		this.factory.disposeAll();
@@ -186,4 +189,13 @@ public void testVarargsCallWithParameter() {
 		boolean wasDeleted = new File("abcdefg.pdf").delete();
 		assertTrue(wasDeleted);
 	}
+
+
+	@Test
+	public void testDisposeMustBeCallableMultipleTimes() {
+		MsWordApp comObj = this.factory.createObject(MsWordApp.class);
+                comObj.Quit();
+                ((ProxyObject) Proxy.getInvocationHandler(comObj)).dispose();
+                ((ProxyObject) Proxy.getInvocationHandler(comObj)).dispose();
+	}
 }