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 tes = 1.0;
double classfled = 2.0;
int wa = 3;

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

tes + classfled / 9 - wa * 1 % 3 + 2

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 clisssen = 8;
boolean cecli = false;
double ba = 2.0;
double iorn = 4.0;

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

!(6 != 3) || 2 == clisssen == 8 < 9 != cecli && 7 != 0 != (ba == iorn)

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" + 7

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:

• Drawing ASTs for expressions: Correct Solution (b36j-j8fu-fdum-xn2y)
• Closures and event handling: Correct Solution (Lzzb-s9fh-zy78-pstx)