Added file write support to new API level 30+

README.md

@@ -1,2 +1,2 @@
 # APKSignReader
-A tool to read Signature on installed APKs
+A tool to read Signature on installed APKs. By providing the target package name the app will read its signatures and save to `/sdcard/Android/data/com.kuro.signreader/files/<package_name>_signatures.txt`

app/src/main/AndroidManifest.xml

@@ -3,6 +3,7 @@
     xmlns:tools="http://schemas.android.com/tools">
 
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
+    <uses-permission android:name="android.permission.QUERY_ALL_PACKAGES"/>
     <application
         android:allowBackup="true"
         android:requestLegacyExternalStorage="true"

app/src/main/java/com/kuro/signreader/MainActivity.java

@@ -85,16 +85,20 @@ public void onClick(View view) {
             @Override
             public void onClick(View view) {
                 try {
-                    String path = appPkg.getText().toString() + "_signatures.txt";
+                    String filename = appPkg.getText().toString() + "_signatures.txt";
+                    File outputFile = new File(getExternalFilesDir(null), filename);
+                    FileOutputStream fos = new FileOutputStream(outputFile);
+
                     StringBuilder sb = new StringBuilder();
-                    sb.append(resultBase64.getText().toString() + "\n");
-                    sb.append(resultCpp.getText().toString() + "\n");
-                    FileOutputStream fos = new FileOutputStream(new File("/sdcard", path));
+                    sb.append(resultBase64.getText().toString()).append("\n");
+                    sb.append(resultCpp.getText().toString()).append("\n");
+
                     fos.write(sb.toString().getBytes());
                     fos.close();
-                    Toast.makeText(MainActivity.this, "Saved to " + path, Toast.LENGTH_SHORT).show();
+
+                    Toast.makeText(MainActivity.this, "Saved to " + outputFile.getAbsolutePath(), Toast.LENGTH_SHORT).show();
                 } catch (Exception e) {
-                    e.printStackTrace();
+                    Toast.makeText(MainActivity.this, "Failed to save: " + e.getMessage(), Toast.LENGTH_LONG).show();
                 }
             }
         });