Help with examples from "Rapid Android Development"

Processing for Android
8

Even though you’ve cached the result of the expression groceries.getString(row, 3) into the variable source:
String source = groceries.getString(row, 3);

You still keep unnecessarily repeating it on your if () {} checks:
if (groceries.getString(row, 3).equals("store")) {

This is how short the check becomes once cache variable source is used instead:
if ("store".equals(source)) {

Anyways, I’ve refactored your sketch w/ some additional tricks in order to make it clearer I hope: :factory:

/**
 * Table TSV Recipe (v2.0.2)
 * by David (2022/Dec/22)
 * mod GoToLoop
 *
 * https://Discourse.Processing.org/t/
 * help-with-examples-from-rapid-android-development/40257/8
 */

static final String
  TSV_FILE = "groceries.tsv", 
  TSV_PARAMS = "header, tsv";

Table groceries;

void setup() {
  size(500, 400);
  noLoop();

  //noStroke();
  fill(0200);
  rectMode(CENTER);

  textSize(24);
  textAlign(CENTER, CENTER);

  groceries = loadTable(TSV_FILE, TSV_PARAMS);
}

void draw() {
  background(0);

  final int rowHeight = height / groceries.getRowCount();

  for (final TableRow row : groceries.rows()) {
    final String
      amount = nullToEmptyStr(row.getString("amount")), 
      unit = nullToEmptyStr(row.getString("unit")), 
      item = nullToEmptyStr(row.getString("item")), 
      source = nullToEmptyStr(row.getString("source"));

    pushStyle();

    switch (source) {
    case "store":
      fill(255, 110, 50);
      break;

    case "market":
      fill(50, 220, 255);
    }

    rect(width >> 1, rowHeight >> 1, width, rowHeight);

    fill(-1);
    text(amount + " " + unit + " " + item, width >> 1, rowHeight >> 1);

    popStyle();
    translate(0, rowHeight);
  }
}

static final String nullToEmptyStr(final String str) {
  return str != null? str : "";
}

amount	unit	item	source
1	pound	flour	store
6	pcs	eggs	market
0.5	table spoon	salt	store
	some cold water
2	pcs	onions	market
1	stick	butter	market
1/4	pound	Gruyere cheese	store
1/4	pound	Emmental cheese	store
1	bunch	chives	market
	taste	salt	store
	taste	pepper	store