First, jdk:http://java.sun.com.
eclipse:http://www.eclipse.org
Android sdk:http://developer.android.com/sdk/index.html
adt:https://dl-ssl.google.com/android/eslipse/(can be installed online, not download)
So now let's talk about the JDK.
JDK (Java development Kit)
The JDK is the core of the entire Java, including the Java Runtime (Java Runtime Envirnment), a stack of Java tools, and a Java-based class library (Rt.jar). Any Java application server is essentially a built-in version of the JDK. So mastering the JDK is the first step to learning Java. The most mainstream JDK is the JDK released by Sun, and in addition to sun, many companies and organizations have developed their own JDK, such as Jrocket, a JDK,BEA company developed by IBM, and a JDK developed by the GNU organization. Where IBM's JDK contains a JVM (Java Virtual machine) that runs much more efficiently than the JVM contained in the Sun JDK. The jrocket running on the x86 platform is also much more efficient than the sun JDK on the service side. But in any case, we need to get the sun JDK in the first place.
Installing the JDK
Set up:
java_home=c:\jdk1.5;
Classpath=.; C:\jdk1.5\lib\tool.jar;c:\jkd1.5\lib\td.jar;
path=c:\jdk1.5\bin\;
Android Development Environment Configuration