int i = 0; /* some comment */
  int j = 0;
  while (i < 10) {
    System.out.println(j);
    i = i + 1;
    j = j + 2*i+1;
  }

INT, Identifier("i"), EQUAL, IntNumeral(0), SEMICOLON, INT, Identifier("j"), EQUAL, ...
WHILE, OPENPAREN, Identifier("i"), LESSTHAN, IntNumeral(10), CLOSEDPAREN, OPENBRACE,
Identifier("System"), DOT, Identifier("out"), ...

Declaration(INT, Identifier("i"), EQUAL, InitialExpression(IntConst(IntNumeral(0)),
  Declaration(INT, Identifier("j"), EQUAL, InitialExpression(IntConst(IntNumeral(0)),
    WhileStatememt(WHILE, OPENPAREN, LessThanExpr(Identifier("i"),LESSTHAN,IntNumeral(10)),
                          CLOSEDPAREN,
      StatementBlock(OPENBRACE,
        Statement(MethodCall(DotExpr(Identifier("System"),DOT,Identifier("out")),DOT,
                   Identifier("println"),
                   OPENPAREN,ArgumentList(Identifier("j")),CLOSEDPAREN),
        SEMICOLON,
          ...
      )
     )
   )
)

Declaration("i",IntType,Some(IntConst(0)),
  Declaration("j",IntType,Some(IntConst(0)),
    WhileStatememt(LessThan(Ident("i"),IntConst(10)),
      StatementBlock(
        MethodCall(DotExpr(Ident("System"),"out"),
                   "println",
                   List(Ident("j"))),
        Assignment("i", Plus(Ident("i"),IntConst(1))),
        Assignment("j", Plus(Ident("j"),
                             Times(IntConst(2),Ident("i"),
                             IntConst(1))
      )
     )
   )
)

Declaration("i",IntType,Some(IntConst(0)),
  Declaration("j",IntType,Some(IntConst(0)),
    WhileStatememt(LessThan(Ident("i"),IntConst(10)),
      StatementBlock(
        MethodCall(DotExpr(Ident("System"),"out"),
                   "println",
                   List(Ident("j"))),
        Assignment("i", TYPE(Plus(TYPE(Ident("i"),INT),IntConst(1))),INT),
        Assignment("j", TYPE(Plus(TYPE(Ident("j"),INT),
                             TYPE(Times(IntConst(2),TYPE(Ident("i"),INT),INT),
                             TYPE(IntConst(1),INT)),INT)
      )
     )
   )
)

i -> (LocalVar,INT)
j -> (LocalVar,INT)

control-flow graph containing three-address code instructions

test.jvm