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 daes = 5;
int tihish = 3;
double aldan = 4.0;

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

5 / daes - tihish % aldan * 1

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 shirc = 7;
int de = 8;
boolean iasir = false;
int ooccar = 9;
double pican = 4.0;

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

(shirc != de && iasir) && 4 == ooccar && pican < 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:

• Class relationships: Correct Solution (rLjh-dwks-hib5-e0om)
• Variable scope and lifetime: Correct Solution (gfcc-38c0-ods2-1k3m)
• Drawing ASTs for expressions: Correct Solution (b5sp-rjtu-3ugL-4w0f)