面向对象编程

类（类似图纸）：是对象共同特征的描述。
对象：是真实存在的具体实例。

在java的编程中必须要先设计类
如何构造类

类名 对象名 = new 类名();
eg: Car c2 = new Car();

访问属性： 对象名.成员变量访问行为：对象名.方法名（…） 总结

// 定义类属性
package createprojection;

public class car {
    // 定义属性
    String name;
    double price;

    // 定义方法
    public void start(){
        System.out.println(name + "价格是" + price+"万元");
    }

    public void run(){
        System.out.println(name + "价格是" + price+"万元");
    }
}

package createprojection;
// 定义对象属性
public class Test {
    public static void main(String[] args) {
        car c = new car();
        c.name = "宝马";
        c.price = 100.35;
        c.start();
        c.run();
        car c2 = new car();
        c2.name = "宝马";
        c2.price = 200;
        c2.start();
        c2.run();
    }
}

运行结果

package createprojection;

public class student {
    String name;
    char sex;
    String hobby;

    public void study(){
        System.out.println();
        System.out.println(name + "性别是:"+sex+";爱好是:"+hobby);
    }
}

package createprojection;

public class Test2 {
    public static void main(String[] args) {
        student s1 = new student();
        s1.name = "小明";
        s1.sex = '男';
        s1.hobby = "打篮球";
        System.out.print("s1:"+s1);
        s1.study();

        System.out.println();

        student s2 = s1;
        System.out.print("s2:"+s2);

        s2.hobby = "爱提问";
        s2.study();


    }

}

黑马程序员