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 fe = 1.0;
int is = 9;
int naloor = 3;
double seda = 3.0;

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

(fe / 8 * is + naloor) + seda

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 ridbe = 2.0;
double seapri = 4.0;
int ac = 4;
int ed = 8;

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

(3 <= 3 || ridbe >= seapri || 3 == ac && ed < 7)

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") + 5

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 (b0fh-okzp-jdqu-p29z)
• Closures and event handling: Correct Solution (Lzc6-1qtt-bz76-1jxk)
• Class relationships: Correct Solution (rfpi-x7pp-o40a-20vu)