第一关类的定义

package step1;// ---------------------Begin------------------------
public class Student{String name="李四";int age=18;public void speak(){System.out.println("我爱学习");}
}// ---------------------End------------------------

第二关类的构造方法与this语句

package step2;
public class Student {// ---------------------Begin------------------------private String name;private int age;Student(){}Student(String n){this.name=n;}Student(int a){this.age=a;}Student(String n,int a){this.name=n;this.age=a;}// ---------------------End------------------------@Overridepublic String toString() {return String.format("大家好我叫：%s，今年：%d岁", this.name, this.age);}
}

第三关类的方法重载

package step3;public class Caculator {public double getArea(double a){return a*a;}// ---------------------Begin------------------------public double getArea(double a,double b){return a*b;}public double getArea(double a,double b,double c){return a*b*c;}// ---------------------End------------------------}

第四关getter与setter方法

package step4;public class Student {private int age;private String name;private String sex;// ---------------------Begin------------------------void setAge(int a){if(a>=0&&a<=120){this.age=a;}else {this.age=18;}}void setSex(String s){if(s.equals("男")||s.equals("女")) this.sex=s;else this.sex="保密";}void setName(String n){this.name=n;}// ---------------------End------------------------@Overridepublic String toString() {return String.format("大家好，我叫：%s,性别：%s，今年：%d", this.name, this.sex,this.age);}
}

第五关static关键字

package step5;public class StaticLearning {// ---------------------Begin------------------------static{System.out.println("类静态代码块被调用");}static void sayHello(){System.out.println("静态方法被调用");}static String name="张三";// ---------------------End------------------------
}