android.app.Application 无法转换为 android.app.Activity [英] android.app.Application cannot be cast to android.app.Activity

问题描述

我正在尝试从另一个类更改 LinearLayout，但是当我运行此代码时:

I'm trying to change a LinearLayout from another class, but when i run this code:

public class IRC extends PircBot {

ArrayList<String> channels;
ArrayList<Integer> userCount;
ArrayList<String> topics;

LinearLayout channelLayout;
Context context;

public IRC(Context ctx) {
    this.setName("xxxx");
    channels = new ArrayList<String>();
    userCount = new ArrayList<Integer>();
    topics = new ArrayList<String>();

    context = ctx;

    channelLayout = (LinearLayout) ((Activity) context).findViewById(R.id.channels);
}

我得到一个 ClassCastException

context 是扩展通过 getApplicationContext() 传递的 Activity 的主要活动；

context is the Main activity that extends Activity passed with a getApplicationContext();

LOGCAT

05-08 17:53:55.102    3736-3799/g.d.allinonechat E/AndroidRuntime﹕ FATAL EXCEPTION: Thread-5357
java.lang.ClassCastException: android.app.Application cannot be cast to android.app.Activity
        at g.d.xxx.IRC.<init>(IRC.java:34)
        at g.d.xxx.MainActivity$1.run(MainActivity.java:49)
        at java.lang.Thread.run(Thread.java:856)

推荐答案

您传递的是 Application Context 而不是 Activity Context 与

You are passing the Application Context not the Activity Context with

getApplicationContext();

无论你在哪里传递它，都通过 this 或 ActivityName.this 代替.

Wherever you are passing it pass this or ActivityName.this instead.

由于您试图将 Context 传递给 Activity 与

Since you are trying to cast the Context you pass (Application not Activity as you thought) to an Activity with

(Activity)

你得到这个异常是因为你不能将 Application 转换为 Activity 因为 Application 不是 Activity 的子类.

you get this exception because you can't cast the Application to Activity since Application is not a sub-class of Activity.

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