Java - 将变量从类传递给类

Question

我知道要从同一个类中传递,我会做这样的事情 - 但是类之间怎么样？

class TestMe{
    public static void main(String[] args)
    {
        int numberAlpha = 232;
        TestMe sendNumber = new TestMe();
        sendNumber.Multiply(numberAlpha);
    }

    void Multiply(int var)
    {
        var+=40;
    }
}

Answer 1

你使用getter和setter.

class A {
    private int a_number;
    public int getNumber() { return a_number; }
}
class B {
    private int b_number;
    public void setNumber(int num) { b_number = num; }
}

..在你的主要方法中,无论它在哪里:

public static void main(String[] args) {
    A a = new A();
    int blah = a.getNumber();
    B b = new B();
    b.setNumber(blah);
}

您还可以使用构造函数作为"初始setter"的方法,以便始终使用已经实例化的最小变量集创建对象,例如:

class A {
    private int a_number;
    public A(int number) { // this is the only constructor, you must use it, and you must give it an int when you do
        a_number = number;
    }
    public int getNumber() { return a_number; }
}