EasyMock

// create
IUnderTest mock = createMock(IUnderTest.class);
//alternatively, to also check method-call-order:
//IUnderTest mock = createStrictMock(IUnderTest.class);
// train
mock.addValue("key", "value");
expect(mock.getValue("key")).andReturn("value"); // expect a call and define what’s returned then
expectLastCall().times(3); // last method call is expected to be called 3 times
expect(mock.deleteValue("nonExistant")).andThrow(new Exception());
//alternatively to last line:
//mock.deleteValue("nonExistant");
//expectLastCall().andThrow(new Exception());

// set mock into “productive” mode
replay(mock);
/* TESTCODE HERE */
// verify trained calls were called like trained
verify(mock);

List<String> l = createMock(List.class);
    // andAnswer style
    expect(l.remove(10)).andAnswer(new IAnswer<String>() {
        public String answer() throws Throwable {
            return getCurrentArguments()[0].toString();
        }
    });

    // andDelegateTo style
    expect(l.remove(10)).andDelegateTo(new ArrayList<String() {
        @Override
        public String remove(int index) {
            return Integer.toString(index);
        }
    });

expect(mock.get("key2"))
  .andReturn("value x1").times(3)
  .andThrow(new Exception(), 4)
  .andReturn("value x2");