# 深入構造器 ## 課堂代碼 ~~~java public class Person { private String name; private int age; private String sex; private String work; private String race; public void setName(String name) { this.name = name; } public String getName() { return name; } public void setAge(int age) { this.age = age; } public int getAge() { return age; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public String getWork() { return work; } public void setWork(String work) { this.work = work; } public String getRace() { return race; } public void setRace(String race) { this.race = race; } //在一個類中，是不允許出現方法簽名相同的方法的 /** * 一下兩個方法實際上執行了方法的重載 * 通俗來講：就是幾個方法，方法名一樣，形參不同 * @param foodName * @param count */ public void eatFood(String foodName, int count) { System.out.println("is eating" + foodName); } public String eatFood(String foodName,String count) { return foodName; } public Person() { } /** * 顯式的創建出有參的構造器，編譯器就不會自動的添加無參構造器 * @param x * @param y */ public Person(String name, int age) { this.name = name;//通過傳入的參數，設置成員變量的值 this.age = age; } //使用this(param)調用其他的構造器 public Person(String name, int age, String sex) { //this();//沒有參數，this()指的是本類的無參構造器 this(name,age);//所以具體this(param)指的是誰，是由傳入的參數類型和個數決定的 this.sex = sex; } /** * 構造器的重載 * @param name * @param age * @param sex * @param work * @param race */ public Person(String name, int age, String sex, String work, String race) { this(name, age, sex); this.work = work; this.race = race; } } ~~~ ~~~java public class Demo { private int a;//只能在本類中被訪問 protected int b; public int c; int d; public static void main(String[] args) { String a = "abc"; String b = new String("abc"); System.out.println(a); System.out.println(b); System.out.println(a == b); System.out.println(a.equals(b)); //本類中 Demo demo = new Demo(); demo.a = 10;//private demo.b = 10;//protected demo.c = 10;//public demo.d = 10;//default } } ~~~ ~~~java public class Test { public static void main(String[] args) { //本包中的類中 Demo demo = new Demo(); demo.b = 10;//protected demo.c = 10;//public demo.d = 10;//default //demo.a = 10; private Person person = new Person(); Person person1 = new Person("徐春林", 24, "男"); System.out.println(person1.getName()); System.out.println(person1.getAge()); System.out.println(person1.getSex()); person1.eatFood("x", 1); } } ~~~