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 phohna = 7;
double lelmal = 2.0;
int iush = 4;

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

(0 + phohna % 9 / lelmal) + iush

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 pe = 5.0;
int scint = 2;
boolean triss = true;
boolean framgri = false;

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

pe >= scint || triss && !framgri || 7 >= 2

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 (rgvp-459k-6ksn-57zn)
• Drawing ASTs for expressions: Correct Solution (b3d5-o0uw-ve1t-p6ey)
• While loops and for loops: Correct Solution (3L80-dcek-kv3a-gir)