一个Java类的封装。

定义一个水果类 Fruit ，包含3个成员变量，分别是 name ，area ， price 设置成私有成员，定义公共方法 get 和 set 方法来读写变量的值。另外定义个测试类 FruitTest ，创建3个对象，设置和输出3种不同水果的信息。

// Fruit.java
public class Fruit {
    private String name;
    private String area;
    private double price;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getArea() {
        return area;
    }

    public void setArea(String area) {
        this.area = area;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }
}

// FruitTest.java
public class FruitTest {
    public static void main(String[] args) {
        Fruit apple = new Fruit();
        apple.setName("苹果");
        apple.setArea("山东");
        apple.setPrice(5.0);
        System.out.println("水果名称：" + apple.getName());
        System.out.println("产地：" + apple.getArea());
        System.out.println("价格：" + apple.getPrice());

        Fruit orange = new Fruit();
        orange.setName("橙子");
        orange.setArea("江西");
        orange.setPrice(4.0);
        System.out.println("水果名称：" + orange.getName());
        System.out.println("产地：" + orange.getArea());
        System.out.println("价格：" + orange.getPrice());

        Fruit banana = new Fruit();
        banana.setName("香蕉");
        banana.setArea("海南");
        banana.setPrice(3.0);
        System.out.println("水果名称：" + banana.getName());
        System.out.println("产地：" + banana.getArea());
        System.out.println("价格：" + banana.getPrice());
    }
}

public class Fruit {
    private String name;
    private double area;
    private double price;
    //无参构造最好加上
    public Fruit() {
    }

    public Fruit(String name, double area, double price) {
        this.name = name;
        this.area = area;
        this.price = price;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getArea() {
        return area;
    }

    public void setArea(double area) {
        this.area = area;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Fruit{" +
                "name='" + name + '\'' +
                ", area=" + area +
                ", price=" + price +
                '}';
    }
}

//测试类

public class FruitTest {
    public static void main(String[] args) {
        Fruit apple = new Fruit();
        apple.setName("苹果");
        apple.setArea(10);
        apple.setPrice(100);
        Fruit orange = new Fruit();
        orange.setName("桔子");
        orange.setArea(8);
        orange.setPrice(66);
        Fruit banana = new Fruit();
        banana.setName("香蕉");
        banana.setArea(20);
        banana.setPrice(166);
        System.out.println(apple.toString());
        System.out.println(orange.toString());
        System.out.println(banana.toString());
    }
}

Java代码如下：

public class Fruit {
    private String name;
    private String area;
    private double price;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getArea() {
        return area;
    }

    public void setArea(String area) {
        this.area = area;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }
}

public class FruitTest {
    public static void main(String[] args) {
        Fruit apple = new Fruit();
        apple.setName("苹果");
        apple.setArea("山东");
        apple.setPrice(5.0);

        Fruit banana = new Fruit();
        banana.setName("香蕉");
        banana.setArea("海南");
        banana.setPrice(3.0);

        Fruit orange = new Fruit();
        orange.setName("橙子");
        orange.setArea("江西");
        orange.setPrice(4.0);

        System.out.println(apple.getName() + "产地：" + apple.getArea() + "，价格：" + apple.getPrice() + "元/斤");
        System.out.println(banana.getName() + "产地：" + banana.getArea() + "，价格：" + banana.getPrice() + "元/斤");
        System.out.println(orange.getName() + "产地：" + orange.getArea() + "，价格：" + orange.getPrice() + "元/斤");
    }
}

输出结果如下：

苹果产地：山东，价格：5.0元/斤
香蕉产地：海南，价格：3.0元/斤
橙子产地：江西，价格：4.0元/斤

public class Fruit {
    private String name;
    private String area;
    private double price;

    public Fruit(String name, String area, double price) {
        this.name = name;
        this.area = area;
        this.price = price;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getArea() {
        return area;
    }

    public void setArea(String area) {
        this.area = area;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }
}

public class FruitTest {
    public static void main(String[] args) {
        Fruit apple = new Fruit("苹果", "山东", 5.1);
        Fruit banana = new Fruit("香蕉", "海南", 3.5);
        Fruit orange = new Fruit("橙子", "江西", 3.8);

        System.out.println("水果信息：");
        System.out.println(apple.getName() + "\t产地：" + apple.getArea() + "\t价格：" + apple.getPrice());
        System.out.println(banana.getName() + "\t产地：" + banana.getArea() + "\t价格：" + banana.getPrice());
        System.out.println(orange.getName() + "\t产地：" + orange.getArea() + "\t价格：" + orange.getPrice());
    }
}