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 nisheoull = 9;
double caesa = 5.0;
double tiossju = 1.0;
double graru = 5.0;
int rakont = 3;
int i = 6;

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

nisheoull * caesa - 4 * 0 / tiossju % 8 * graru - rakont * 3 % i

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 e = 5;
int blosmost = 9;
boolean eol = true;
int spesmspru = 9;
boolean stom = true;
double ri = 5.0;

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

e < 9 && 1 == 0 != 3 <= 6 == 6 <= blosmost == 6 >= 8 && eol != spesmspru <= 9 == !!stom == !(3 >= ri)

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 + 8 + 9) + 10

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:

• While loops and for loops: Correct Solution (tkji-tp4u-e4mv-78)
• Closures and event handling: Correct Solution (Lvri-rwcy-n18k-cL6r)