ensure a zip file by file content.

jadx-core/src/main/java/jadx/core/utils/files/FileUtils.java

@@ -11,6 +11,8 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.util.jar.JarEntry;
 import java.util.jar.JarOutputStream;
+import java.util.zip.ZipException;
+import java.util.zip.ZipFile;
 
 import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
@@ -100,4 +102,22 @@ public class FileUtils {
 		makeDirsForFile(file);
 		return file;
 	}
+
+	public static boolean isZipFile(final File file) throws IOException {
+		ZipFile zipFile = null;
+		try {
+			zipFile = new ZipFile(file);
+			return zipFile.entries().hasMoreElements();
+		} catch (ZipException e) {
+			return false;
+		} finally {
+			if (zipFile != null) {
+				try {
+					zipFile.close();
+				} catch (IOException e) {
+					LOG.error(e.getMessage());
+				}
+			}
+		}
+	}
 }

jadx-core/src/main/java/jadx/core/utils/files/InputFile.java

@@ -52,15 +52,12 @@ public class InputFile {
 			addDexFile(loadFromClassFile(file));
 			return;
 		}
-		if (fileName.endsWith(".apk") || fileName.endsWith(".zip")) {
-			loadFromZip(".dex");
-			return;
-		}
-		if (fileName.endsWith(".jar")) {
-			// check if jar contains '.dex' files
+		if (FileUtils.isZipFile(file)) {
+			// check if zip contains '.dex' files
 			if (loadFromZip(".dex")) {
 				return;
 			}
+			if (fileName.endsWith(".jar")) {
 				addDexFile(loadFromJar(file));
 				return;
 			}
@@ -68,6 +65,8 @@ public class InputFile {
 				loadFromZip(".jar");
 				return;
 			}
+			return;
+		}
 		//throw new DecodeException("Unsupported input file format: " + file);
 	}