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 anhe = 2;
int douck = 5;
double desnir = 5.0;

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

anhe + douck / (9 % 7) - desnir

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 he = true;
boolean ced = true;
boolean mashris = false;

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

(he || 3 > 1 || ced) || mashris

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 declarations and object modeling: Correct Solution (17xi-vfdd-2z5i-vkg6-L)
• Closures and event handling: Correct Solution (Lwuu-qvcb-ao6y-a3Li)