Study Notes for Android section 2 helloworld Program

1. helloworldProgram

Create an AVD, that is, the simulator. In the toolbar, click the SDK and AVD manager buttons, and then new. The configuration is shown in the left figure. After the configuration is complete, as shown in the right figure, click Start.

 

Create an android project, set it as follows, and click Android Application in run

The result is displayed? If nothing is written, there will be helloworld.

 

2. Associate the class file

We often need to check the source file. The default value is javadoc, but sometimes we still need to check the source file (that is, press Ctrl and click to see the Java file). solution:

First download the SRC file: android-2.2-src.zip: http://u.115.com/file/f1c7946c3c

Next, create a source folder under the SDK root directory in the previous section and put the downloaded ZIP file into it. Other versions can be downloaded later.

Finally, in the project, select an activity, press Ctrl, and click. You cannot see the activity, and attach source file... Select the SRC file in the new window and click OK.

 

3. Introduce the project structure: too many!

R. Java: Do not manually modify

Assets: resource files, music files, videos, and so on. All items are packaged in the package, whether or not they are used.

Res: it is a resource file, image, etc. It will be packaged only when used.

Main. XML in layout is very important. layout management of this application

String. XML in values is also very important, and some fixed strings are configured.