2. Click to select apk or ROM, which is used to select ROM or apk to be signed, as shown in the figure.

3. Click the directory where the signature file is saved, and set the location where the signature ROM is stored. I'll put it here on the desktop and click Make Signature.

This will prompt that it is being made. Please pay attention here. If you just click Make Signature, it indicates success, which means that Java is not installed on your computer. Please install Java first. See the second lecture in this series for details.

5. Act successful. The place where you store it is another ROM with the same name, but there are more symbols behind it. This ROM is the ROM after signing the contract, just like the previous ROM. ROM can only be swiped after signing the contract.

How to compile and decompile with apktools;

1. Open apktools and select the apk file to decompile. Same as above, you need to set the decompilation storage path.

Click to decompile.

2. The sign of successful decompilation is that there is a folder in your storage path, and there are apk icons, actions and so on in this folder. How to modify it will be discussed later.

3. Compile is to repackage the decompiled folder into apk files, so choose the folder you modified, choose the compilation and saving path, and compile.

4. The sign of successful compilation is that there is an apk file in your storage path, which is a newly modified Android software. Note that it needs to be signed after compilation, otherwise it cannot be installed.