1. Online installation:
Start eclipse, in the Help menu, select install new software..., select available software, click Add site... on the right, enter https://dl-ssl.google.com/android/eclipse/
You can follow the prompts in the subsequent steps.
2. Offline installation (local installation)
2.1 Download an ADT installation package directly. After decompression, there should be two folders, plugins and features. Find these two folders in your eclipse, copy plugins and features in adt to the plugins and features folders of eclipse respectively.
2.2 download the ADT installation package to the terminal. For example, we will download adt-10.zip
In eclipse, select "Help-> install new software... ", in the open install dialog box, click" add... "button to open the Add site dialog box. Enter ADT in the name column and click" archive... "click" Next ", select the downloaded adt-10.zip file, and click" OK)