Java 構造器

package com.neusoft.oop;
/**
 * 構造函數(構造器)：它就是一種特殊的方法，主要的作用是可以給類中的變量進行初始化。
 * 1.構造方法的名稱 與類名相同
 * 2.構造方法是沒有返回值的
 * 3.一般來說構造方法都是public的
 * 
 * 構造方法如何調用：new ConstructorDemo()
 * @author Administrator
 *
 */
public class ConstructorDemo {
	
	public ConstructorDemo(){
		System.out.println("Constructor ........");
	}
	
	public int test1(){
		System.out.println("test1......");
		return 0;
	}
	public static void main(String[] args) {
		new ConstructorDemo().test1();
	}
}

package com.neusoft.oop;
/**
 * 之前我們會將屬性聲明在類中，如何給屬性賦值 對象名.屬性名，這樣做是不好的，因爲直接操作了屬性
 * 如何將類中的屬性進行初始化(賦值)
 * 1.get/set方法
 * 2.構造器
 * @author Administrator
 *
 */
public class ConstructorDemo2 {
	private String username;
	private String password;
	private int age;
	private String school;
	
	public ConstructorDemo2(String username, String password, int age, String school) {
		this.username = username;
		this.password = password;
		this.age = age;
		this.school = school;
		System.out.println("12345648915");
	}
	
	public static void main(String[] args) {
		ConstructorDemo2 constructorDemo2 = new ConstructorDemo2();
		constructorDemo2.username = "tom";
		//可以給外部類使用，將屬性加上private就可以隱藏
	}

	public String getUsername() {
		return username;
	}
	//給屬性設置一個值
	public void setUsername(String username) {
		this.username = username;
		
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getSchool() {
		return school;
	}

	public void setSchool(String school) {
		this.school = school;
	}
}

package com.neusoft.oop;

public class ConstructorDemo2Test {
	public static void main(String[] args) {
		ConstructorDemo2 constructorDemo2 = new ConstructorDemo2("tom", "123456", 30, "neusoft");
		// constructorDemo2.setUsername("tom");
		// String username = constructorDemo2.getUsername();
		// System.out.println(username);
		System.out.println(constructorDemo2.getUsername());

		constructorDemo2.setAge(20);
		int a = constructorDemo2.getAge();
		System.out.println(a);

		constructorDemo2.setPassword("123456");
		String password = constructorDemo2.getPassword();
		System.out.println(password);

		constructorDemo2.setSchool("大連大學");
		String school = constructorDemo2.getSchool();
		System.out.println(school);

	}

}