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 mistfec = 5;
int phiw = 2;
int hishe = 1;
int picid = 3;

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

1 % (mistfec % 7 % phiw / 3 + hishe) / picid

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 siapu = 9;
double sidci = 3.0;
int fecchin = 9;
int ieu = 8;
boolean marddurd = true;

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

(5 > 2 != siapu > 3 == 5 > sidci) && fecchin >= 7 || 8 <= ieu == marddurd

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:

• Static and runtime types: Correct Solution (wtuw-bzyq-x33n-3sr1)
• Closures and event handling: Correct Solution (Lxrb-jdmu-6nsu-2xy0)