application全局变量-优快云博客

本文链接：https://blog.youkuaiyun.com/iteye_15461/article/details/81931033

本文介绍了一个简单的Android应用程序中实现导航功能的方法。通过继承Application类并维护一个Item列表，确保了应用状态的一致性。DetailActivity类负责显示列表项详情，并通过按钮点击事件实现了基本的前后切换功能。

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注意添加application android:name="YourAppName" public class YourAppName extends Application { private List<Item> mItems; @Override public void onCreate() { super.onCreate(); mItems = getYourItemList(); } public List<Item> getItems() { return mItems; } }

public class DetailActivity extends Activity {
  private YourAppName mApp;
  private ImageButton mNextButton;
  private ImageButton mBackButton;
  private TextView mTitle;
  private int mIndex;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.your_layout);
    mApp = (YourAppName) getApplication();

    /*This index should come from the intent */
    mIndex = 2; 
    getWidgets();
    populateWidgets();
  }

  private void getWidgets() {
    mNextButton = (ImageButton)findViewById(R.id.next);
    mTitle = (TextView)findViewById(R.id.title);
    /* other findViewById */

    mNextButton.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
           mIndex++; /*Notice that this will get a NPE.
                     You need to place a better logic here */
           populateWidgets();
        }
    });
  }

  private void populateWidgets() {
    Item item = mApp.getItemList().get(mItem);
    mTitle.setText(item.getName());
  }
}