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 trilprol = 4.0;
int fu = 6;

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

5 / 5 * trilprol + 7 / fu / 5

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 leded = false;
double en = 2.0;
int bulreest = 5;
double xort = 3.0;
double coc = 4.0;
boolean slasm = true;

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

leded && (en != 3 == bulreest <= xort) || 1 == coc || slasm

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 + 6

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:

• Static and runtime types: Correct Solution (wtns-35sp-gh40-acid)
• Drawing ASTs for expressions: Correct Solution (b2i3-unvz-59j1-apcx)