1:
URI:Universal Resource Identifier,通用资源标识符;
URL:Uniform Resource Locator,统一资源定位符;
URN:Uniform Resource Name,统一资源名称。其中,URL,URN是URI的子集。
:2:
An internal error occurred during: "Launching MainActivity".
java.lang.NullPointerException
的解决方法:
Project->Properties->Run/DebugSettings:
1.select"LaunchingNew_configuration"
2.Delete
3.OK