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 chrerpon = 3.0;
int kla = 1;
int iop = 8;

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

8 % chrerpon + kla + iop - 7

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 momea = 4;
boolean lal = true;

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

2 != momea && 1 > 6 || 0 >= 4 || lal

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"

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 (aze0-kssg-01e6-xhyc)
• Stack frames and objects (like the Idea Lab activity): Correct Solution (1d9h-yfr2-xx4t-12hp-3)