return语句后的意外输出

Question

我有以下代码：

public class MainClass {

    static int someStaticVariable = 0;

    public static void main(String[] args) {

        MainClass obj = new MainClass();
        obj.someInstanceMethod();
        System.out.println("Count in main method " + someStaticVariable);
    }

    public int someInstanceMethod() {

        String someString = "line1\nline2\n";

        System.out.println("Count in someInstanceMethod method "
                    + (someStaticVariable + someString.split("\r\n|\r|\n").length));

        return (someStaticVariable + someString.split("\r\n|\r|\n").length);

    }
}

问题：为什么输出为：

Count in someInstanceMethod method 2
Count in main method 0

而非

Count in someInstanceMethod method 2
Count in main method 2

以及为什么它会在someInstanceMethod中打印到Count in someInstanceMethod method 2并返回0然后在main方法中打印0。

Answer 1

您没有为someStaticVariable分配任何内容;你忽略了someInstanceMethod的回归。尝试

someStaticVariable = obj.someInstanceMethod();

或者，您可以在方法本身中分配它。

someStaticVariable += someString.split("\r\n|\r|\n").length;
return (someStaticVariable + someString.split("\r\n|\r|\n").length);

Answer 2

问题在于您不会篡改someStaticVariable。

您只需打印出someStaticVariable（即0）和someString.split("\r\n|\r|\n").length

的总和

您需要做的是分配：

someStaticVariable = obj.someInstanceMethod();