如何声明TextView变量，以便可以在任何地方使用它? [英] How do I declare a TextView variable so that I can use it anywhere?

问题描述

我今天才开始用java/android进行编码，请原谅我在这里是个白痴.

I have started coding in java/android just today so excuse me if I am being a total idiot here.

过去一个小时我一直在面对这个问题，我曾尝试用Google搜索它，但找不到任何答案.

I have been facing this problem for the past hour, I have tried to google it but couldn't find any answers.

如何将TextView声明为静态/变量，以便只需键入变量名"即可访问它.我代码中的任何地方?

How do I declare a TextView as a static/variable so that I can access it simply by typing "variablename." anywhere in my code?

我不是试图从另一个活动访问TextView，这些都在同一个活动中.

I am not trying to access the TextView from another activity, these are all in the same one.

这是我的代码的样子(全部在mainactivity.java中):

This is what my code looks like(all in mainactivity.java) :

public class MainActivity extends Activity {

    TextView test = (TextView)findViewById(R.id.textView2);

    public void registermessage(View view) {
        test.setText("Test");
    }
}

这不会在Eclipse中产生任何错误，而只是在我尝试在手机上运行时将其强制关闭.

This doesn't give any errors in Eclipse but will simply force close when I try to run it on my phone.

当我将声明为textview的行移动到公共void上时，我可以成功，但是我希望能够从活动中的任何void中使用变量test.

I can succeed when I move the line I declare test as a textview to the public void but I want to be able to use the variable test from any void in the activity.

谢谢！

推荐答案

在调用 setcontentView 方法之后，您必须实例化变量，因此您必须执行以下操作:

You have to instantiate the variable after the setcontentView method was called, so you have to do the following:

public class MainActivity extends Activity {

TextView test;

@Override
onCreate(Bundle s){
    ...
    setContentView(R.layout.yourLayout);
    test = (TextView)findViewById(R.id.textView2);
}


public void registermessage(View view) {

    test.setText("Test");
}

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