android - 从 onResume() 方法访问 Viewpager 中的 TextView.setText()

Question

我是 Android 开发的新手，所以我遇到了 onResume() 方法的问题。

当我尝试从 onResume() 方法中编写 Name.setText() 时，我的代码崩溃了。 从 onPause() 方法中编写 TextView 的工作出奇地没有任何问题。

如何从 onResume() 方法中访问此 TextView？

public class Main extends Activity {

    private ViewPager awesomePager;
    private static int NUM_AWESOME_VIEWS = 2;
    private Context cxt;
    private AwesomePagerAdapter awesomeAdapter;
    View v;
    TextView Name;


    /** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    cxt = this;

    awesomeAdapter = new AwesomePagerAdapter();
    awesomePager = (ViewPager) findViewById(R.id.awesomepager);
    awesomePager.setAdapter(awesomeAdapter);

}

@Override
protected void onResume() {
    super.onResume();
    Name.setText("1");

}

@Override
protected void onPause() {
    super.onPause();

}

private class AwesomePagerAdapter extends PagerAdapter{

            @Override
            public int getCount() {
                    return NUM_AWESOME_VIEWS;
            }

            @Override
            public Object instantiateItem(View collection, int position) {

                View v = new View(cxt.getApplicationContext());
                final LayoutInflater inflater = (LayoutInflater) cxt
                        .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

                switch (position) {

                case 0:

                    v = inflater.inflate(R.layout.subpage1, null, false);
                    Name = (TextView) v.findViewById(R.id.name);

                    break;

                case 1:

                    v = inflater.inflate(R.layout.subpage2, null, false);

                    break;

                default:

                    break;
                }

                ((ViewPager) collection).addView(v, 0);

                return v;       

            }

            @Override
            public void destroyItem(View collection, int position, Object view) {
                ((ViewPager) collection).removeView(v);

            }

            @Override
            public boolean isViewFromObject(View view, Object object) {
                return view == object;
            }

            @Override
            public void finishUpdate(View arg0) {}

            @Override
            public void restoreState(Parcelable arg0, ClassLoader arg1) {}

            @Override
            public Parcelable saveState() {
                    return null;
            }

            @Override
            public void startUpdate(View arg0) {}             

}
}

Answer 1

Name 必须设置为 null...您的应用程序必须在初始化之前暂停。在尝试对其进行任何操作之前，只需检查以确保它已初始化。你的 onResume() 应该看起来像这样:

@Override
protected void onResume() {
  super.onResume();
  if(Name != null){
    Name.setText("1");
  }
}

附言标准的 Java 约定是让所有变量名都以小写字母开头。您可能应该将 Name 重命名为 name。