Java語言_以類別為藍圖建立物件程式碼

package com.sample;

import static java.lang.System.out;

class Boy {

    public Boy() {
        out.println("Boy constructor one");
    }

    public Boy(int n) {
        out.println("Boy constructor two, n = " + n);
    }

    public void hello(String name) {
        out.println(name + " say hello method.");
    }
}

public class JavaProject21 {

    public static void main(String[] args) {

        Boy boy1 = new Boy();
        boy1.hello("boy1");
        out.print("\n");

        Boy boy2 = new Boy(16);
        boy2.hello("boy2");
        out.print("\n");

        Boy boy3 = null;
        boy3 = new Boy(20);
        boy3.hello("boy3");
    }
}