Java Programming Flowchart: Cheat Sheet

Symbols

Shape	Name	Java
	Terminal: start/end	main begins/ends
	Input/Output	sc.nextInt(), println
	Process	= ++ += math
	Decision: 2 exits (T/F)	if, loop tests
	On-page connector	joins lines
	Off-page connector	continues on next page
	Predefined process	method call
	Preparation (optional)	for setup

Three control structures

Drawing rules

• One Start, at least one End. Every path must reach End.
• Flow is top → bottom, left → right.
• Label both diamond exits: True/False or Yes/No.
• One action per symbol and short text.
• No crossing lines: use connectors.

Selection in Java

if (n < 0) { n = -n; }            // if: one path

if (score >= 75) println("Pass"); // if-else:
else             println("Fail"); // exactly one runs

if (s >= 90) ...                  // else-if ladder:
else if (s >= 80) ...             // False -> next diamond
else ...                          // first True wins

switch: one diamond per case, default = last False path. No break means it falls through to the next case.

Loops in Java

int i = 1;             // initialize (before loop)
while (i <= 5) {       // test = diamond
    println(i);        // body
    i++;               // update, then back to test
}

for (int i = 1; i <= 5; i++) { ... }  // same shape

do {                   // body FIRST
    ...
} while (x < 5);       // test LAST (note the ;)

Loop	Test	Min runs
while	pre-test (before body)	0
for	pre-test (before body)	0
do-while	post-test (after body)	1

• Counter-controlled: known count (for).
• Sentinel-controlled: stop on a special value, e.g. -1.
• break: arrow straight to the loop exit.
• continue: skip to the update/test.

Code → flowchart in 6 steps

• Start of main → Start
• sc.next…() / println → parallelogram
• =, ++, math → rectangle
• if / loop condition → diamond
• Loop → arrow back to the diamond
• End of main → End

Common mistakes

• Using a rectangle for println. It's Output (parallelogram).
• Unlabeled diamond exits.
• sum = 0 inside the loop (it resets every pass).
• No update → infinite loop.
• Loop arrow going back to Start instead of the diamond.