Simplify *Transfer check* methods

* instanceof already checks nulls
* String.isEmpty used

Author: akurtakov

bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/gtk/org/eclipse/swt/dnd/ByteArrayTransfer.java

@@ -192,6 +192,6 @@ protected Object nativeToJava(TransferData transferData) {
 }
 
 boolean checkByteArray(Object object) {
-	return (object != null && object instanceof byte[] && ((byte[])object).length > 0);
+	return (object instanceof byte[] && ((byte[])object).length > 0);
 }
 }

bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/gtk/org/eclipse/swt/dnd/HTMLTransfer.java

@@ -122,7 +122,7 @@ protected String[] getTypeNames() {
 }
 
 boolean checkHTML(Object object) {
-	return (object != null && object instanceof String && ((String)object).length() > 0);
+	return (object instanceof String && !((String)object).isEmpty());
 }
 
 @Override

bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/gtk/org/eclipse/swt/dnd/ImageTransfer.java

@@ -171,7 +171,7 @@ protected String[] getTypeNames(){
 }
 
 boolean checkImage(Object object) {
-	if (object == null || !(object instanceof ImageData)) return false;
+	if (!(object instanceof ImageData)) return false;
 	return true;
 }
 

bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/gtk/org/eclipse/swt/dnd/RTFTransfer.java

@@ -118,7 +118,7 @@ protected String[] getTypeNames() {
 }
 
 boolean checkRTF(Object object) {
-	return (object != null && object instanceof String && ((String)object).length() > 0);
+	return (object instanceof String && !((String)object).isEmpty());
 }
 
 @Override

bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/gtk/org/eclipse/swt/dnd/TextTransfer.java

@@ -161,7 +161,7 @@ protected String[] getTypeNames() {
 }
 
 boolean checkText(Object object) {
-	return (object != null && object instanceof String && ((String)object).length() > 0);
+	return (object instanceof String && !((String)object).isEmpty());
 }
 
 @Override