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 cesdo = 2.0;
int piissur = 4;

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

9 - cesdo * (6 % piissur)

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:

boolean tedtust = false;
int oi = 5;
int boeshcod = 8;
double onud = 1.0;

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

tedtust && oi >= 7 && boeshcod > onud

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 + 4

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:

• Drawing ASTs for expressions: Correct Solution (b2du-9ypt-36b9-i6b2)
• Static and runtime types: Correct Solution (wtmf-utbn-6qm4-jxeo)