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:

int gourddont = 8;
int tezal = 4;
int gringca = 2;

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

gourddont * tezal * gringca

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:

double clior = 4.0;
int olwhed = 2;
int sphon = 4;

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

clior == olwhed || sphon > 6

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:

• Booleans and conditionals: Correct Solution (5iLd-dajq-nbxs-q9m8)
• Class relationships: Correct Solution (rg2d-6fzv-z9kw-d3jt)