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 sixas = 7;
double samioc = 3.0;

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

sixas - 4 - 9 / samioc

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 dilcet = false;
int clasm = 4;
boolean ip = false;

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

dilcet && (clasm < 8 || ip)

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

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:

• Closures and event handling: Correct Solution (Lxti-1cb9-zz83-6xxe)
• Drawing ASTs for expressions: Correct Solution (b2xr-ersg-zdpx-9um8)