Android 从另一个类调用方法 [英] Android Call a method from another class

问题描述

我知道这个问题重复了，但我在网上找不到答案.

I know that this Question is repeated but I can't find the answer in the Internet.

我想从另一个类调用一个方法.

I want to call a method from another class.

我有 Class1 和 Class2.

I have Class1 and Class2.

在第 2 类我有这个方法:

In Class 2 I have this method:

public void UpdateEmployee(){
    //some code
}

我想从 Class1 调用上面的方法.

I want to call the above method from Class1.

感谢您的回答.

----编辑----

final Button btnUpdate = (Button)findViewById(R.id.btnUpd);
   btnUpdate.setOnClickListener(new View.OnClickListener() {      
     public void onClick(View v) {
             Employee updEmple = new Employee();
             updEmple.UpdateEmployee();      
            
    }
    });

----LogCat---

----LogCat---

05-28 16:30:44.030: E/AndroidRuntime(25198): FATAL EXCEPTION: main
05-28 16:30:44.030: E/AndroidRuntime(25198): java.lang.NullPointerException: println    needs a message
05-28 16:30:44.030: E/AndroidRuntime(25198):    at android.util.Log.println_native(Native Method)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at android.util.Log.v(Log.java:116)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at   and.net.Employee.UpdateEmployee(Employee.java:77)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at and.net.AndActivity$2.onClick(AndActivity.java:51)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at android.view.View.performClick(View.java:2485)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at android.view.View$PerformClick.run(View.java:9080)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at android.os.Handler.handleCallback(Handler.java:587)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at android.os.Handler.dispatchMessage(Handler.java:92)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at android.os.Looper.loop(Looper.java:123)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at android.app.ActivityThread.main(ActivityThread.java:3683)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at java.lang.reflect.Method.invokeNative(Native Method)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at java.lang.reflect.Method.invoke(Method.java:507)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-28 16:30:44.030: E/AndroidRuntime(25198):    at  dalvik.system.NativeStart.main(Native Method)

推荐答案

你应该使用以下代码:

Class2 cls2 = new Class2();
cls2.UpdateEmployee();

如果您不想创建一个新实例来调用该方法，您可以将该方法声明为 static，然后您只需调用 Class2.UpdateEmployee().

In case you don't want to create a new instance to call the method, you can decalre the method as static and then you can just call Class2.UpdateEmployee().

这篇关于Android 从另一个类调用方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！