[英]Method call from a class in a separate file
I'm a complete noob obviously, but i'm trying to make a simple dummy application for a university project and i don't see what i'm doing wrong. 我显然是一个完整的菜鸟,但是我正在尝试为一个大学项目制作一个简单的虚拟应用程序,但是我看不出我做错了什么。 I'm not very skilled at Java, so that could be a part of the problem, but i've been looking at examples and i still can't figure it out.
我不太熟练Java,所以这可能是问题的一部分,但是我一直在查看示例,但仍然无法弄清楚。
I've simplifed it to the best of my ability and it still won't work. 我已尽其所能简化了它,但仍然无法使用。 so, i have 2 .java files in the same package
所以,我在同一包中有2个.java文件
test.java:
package com.example.test;
import android.app.Activity;
import android.os.Bundle;
public class test extends Activity {
public int zapis;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void onStart() {
super.onStart();
test2 klasa = null;
zapis = klasa.a;
}
}
and test2.java: 和test2.java:
package com.example.test;
public class test2 {
public int a=3;
}
and if i run it, the app crashes :( What am i missing, some kind of a constructor? Thanks for your help. 如果我运行它,该应用程序将崩溃:(我缺少什么,某种构造函数?感谢您的帮助。
If you want to access an object's members you first need to create the object. 如果要访问对象的成员,则首先需要创建对象。
replace 更换
test2 klasa = null;
with 与
test2 klasa = new test2();
and it should work. 它应该工作。
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