学习Java第十一天--面向对象之方法重载、构造方法

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public class Person {
public void eat(food a) {
//食物放入口中
//咀嚼
//咽下
}
public void eat(pill a) {
//食物放入口中
//喝水
//咽下
}
public void eat(chutty a) {
//食物放入口中
//咀嚼
//吐出
}
}

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public class TestCalculator {
public static void main(String[] args) {
Calculator calc1 = new Calculator();
System.out.println(calc1.add(5, 6));
System.out.println(calc1.add(10.2 , 11.3 , 15.6 ));
}
}
//计算器
class Calculator{
public double add(double num1 , double num2) {
return num1 + num2;
}
public double add(double num1 , double num2 , double num3) {
return num1 + num2 + num3;
}
}

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public class TestConstractor {
public static void main(String[] args) {
//1.执行new Student2()构造对象
//1.1 堆内存中开辟对象空间
//1.2 将构造后的对象地址，赋值给stu1变量
Student2 stu1 = new Student2();
stu1.sayHi();
}
}
class Student2{
String name;
int age;
char sex;
double score;
public Student2() {
//2.构造方法执行过程分两步：
//2.1 初始化属性
//2.2 执行构造方法中的逻辑代码
System.out.println("---无参的构造方法---");
}// 执行完构造方法后返回方法调用处
public void sayHi() {
System.out.println("Hello");
}
}

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public class TestConstractorOverload {
public static void main(String[] args) {
new Teacher2();
new Teacher2("jake");
new Teacher2("Alex" , 30);
}
}
class Teacher2{
String name;
int age;
String sex;
double salary;
public Teacher2() {
System.out.println("---无参的构造方法---");
}
public Teacher2(String n) {
System.out.println("---1参的构造方法---");
}
public Teacher2(String n , int a) {
System.out.println("---2参的构造方法---");
}
}

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public class TestConstructors{
public static void main(String[] args){
Student s = new Student("tom",20,"man","98.5");
System.out.println(s.name+"t"+s.age+"t"+s.sex+"t"+s.score);
}
}
class Student{
String name;
int age;
String sex;
double score;
public Student(String n,int a,String s,double sc){//由构造方法为各个属性赋值
name = n;
age = a;
sex = s;
score = sc;
}
}

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public class TestThisKeyword {
public static void main(String[] args) {
Student3 str = new Student3("tom" , 20 , "male" , 99.8);
str.sayHi();
}
}
class Student3{
String name;
int age;
String sex;
double score;
public Student3(){}
public Student3(String name) {
this();//this([实参]);必须写在构造方法的首行；仅可在构造方法中使用
System.out.println("---1参的构造方法---");
this.name = name;
}
public Student3(String name , int age) {
this(name);
System.out.println("---2参的构造方法---");
this.age = age;
}
public Student3(String name , int age , String sex) {
this(name , age);
System.out.println("---3参的构造方法---");
this.sex = sex;
}
public Student3(String name , int age , String sex , double score) {
this(name , age , sex );
System.out.println("---4参的构造方法---");
this.score = score;
}
public void sayHi() {
System.out.println(this.name+"t"+this.age+"t"+this.sex+"t"+this.score);
}
}