Java Basic(17)-Constructors

class apples{

public static void main(String args[]){

tuna tunaObject = new tuna ();

tunaObject.saying();

}

}

如果運行這個程序，其結果將是： Your first gf was null

結果是null的，因為他們不知道在tuna.java的girlName的值是什麼

因此，在tuna.java的private String girlName;下面加上:

public tuna(String name){

girlName=name;

}

In apples.java:

class apples{

public static void main(String args[]){

tuna tunaObject = new tuna ("Emily "); → 把字符串的值在這裡

tuna tunaObject2 = new tuna ("Sally");

tunaObject.saying();

tunaObject2.saying();

}

}

運行這個程序，你會看到：

Your first gf was Emily Your first gf was Sally