Drawing ASTs for expressions: Correct Solution

For each of the Java expressions below:

• Draw an AST for the expression.
• Show how the expression evaluates at each node in the tree.

Be sure that your tree accurately reflects how Java would evaluate the expression.

Part 1

Given the following variables:

double rimca = 2.0;
int trasna = 5;
double ephrol = 2.0;

...draw the AST and evaluation results for the following expression:

(rimca * trasna) / ephrol

Solution

Things to double-check in your solution:

• Do you have the left and right branches on the correct side?
• Did you indicate the difference between ints and floating point values?

Part 2

Given the following variables:

int praesin = 8;
int piachpar = 1;

...draw the AST and evaluation results for the following expression:

praesin <= piachpar && 3 != 0

Solution

Things to double-check in your solution:

• Does your tree correctly reflect the precedence of && and ||?
• Did you correctly show short-circuiting? (That is when the right branch of && or || is never evaluated because the left branch already determines the answer.)

Part 3

Draw the AST and evaluation results for the following expression:

0 + 1 + "2" + 3

Solution

Things to double-check in your solution:

• Did you indicate the distinction between ints and Strings?
• Are your left/right branches correct?

Related puzzles:

• Class declarations and object modeling: Correct Solution (17u7-octp-5n7s-7gfj-r)
• Drawing ASTs for expressions: Correct Solution (azvc-9b4e-Lp66-84rk)
• Class relationships: Correct Solution (regk-y1nf-041c-jmsf)