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There is a class named Robot in Java SE. Read the API doc for more info.
Java Platform SE 6

Can you explain your problem?
What is the code you posted supposed to do? What does it do?
Have you tried debugging the code by adding printlns to show the values of variables and the execution...

Your code is defining two different variables with the name end (note variable names should start with lowercase letter). Use the existing variable: end inside of the loop. Do not define a new one:
...

Where in the loop do you change either of the values being tested in the while condition?