java-tutorials/spring-5/src/main/java/com/baeldung/assertions/Car.java

package com.baeldung.assertions;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.springframework.util.Assert;

public class Car {
    private String state = "stop";

    public void drive(int speed) {
        Assert.isTrue(speed > 0, "speed must be positive");
        this.state = "drive";
        // ...
        if (!(speed > 0)) {
            throw new IllegalArgumentException("speed must be >0");
        }
    }

    public void stop() {
        this.state = "stop";
    }

    public void fuel() {
        Assert.state(this.state.equals("stop"), "car must be stopped");
        // ...
    }

    public void fuelwithSupplier() {
        Assert.state(this.state.equals("stop"), () -> "car must be stopped");
        // ...
    }

    public void сhangeOil(String oil) {
        Assert.notNull(oil, "oil mustn't be null");
        // ...
    }

    public void replaceBattery(CarBattery carBattery) {
        Assert.isNull(carBattery.getCharge(), "to replace battery the charge must be null");
        // ...
    }

    public void сhangeEngine(Engine engine) {
        Assert.isInstanceOf(ToyotaEngine.class, engine);
        // ...
    }

    public void repairEngine(Engine engine) {
        Assert.isAssignable(Engine.class, ToyotaEngine.class);
        // ...
    }

    public void startWithHasLength(String key) {
        Assert.hasLength(key, "key must not be null and must not the empty");
        // ...
    }

    public void startWithHasText(String key) {
        Assert.hasText(key, "key must not be null and must contain at least one non-whitespace  character");
        // ...
    }

    public void startWithNotContain(String key) {
        Assert.doesNotContain(key, "123", "key must not contain 123");
        // ...
    }

    public void repair(Collection<String> repairParts) {
        Assert.notEmpty(repairParts, "collection of repairParts mustn't be empty");
        // ...
    }

    public void repair(Map<String, String> repairParts) {
        Assert.notEmpty(repairParts, "map of repairParts mustn't be empty");
        // ...
    }

    public void repair(String[] repairParts) {
        Assert.notEmpty(repairParts, "array of repairParts must not be empty");
        // ...
    }

    public void repairWithNoNull(String[] repairParts) {
        Assert.noNullElements(repairParts, "array of repairParts must not contain null elements");
        // ...
    }

    public static void main(String[] args) {
        Car car = new Car();

        car.drive(50);

        car.stop();

        car.fuel();

        car.сhangeOil("oil");
        
        CarBattery carBattery = new CarBattery();
        car.replaceBattery(carBattery);

        car.сhangeEngine(new ToyotaEngine());

        car.startWithHasLength(" ");
        car.startWithHasText("t");
        car.startWithNotContain("132");

        List<String> repairPartsCollection = new ArrayList<String>();
        repairPartsCollection.add("part");
        car.repair(repairPartsCollection);

        Map<String, String> repairPartsMap = new HashMap<String, String>();
        repairPartsMap.put("1", "part");
        car.repair(repairPartsMap);

        String[] repairPartsArray = { "part" };
        car.repair(repairPartsArray);

    }
}