问题描述

Android 的 Tab 不能正常运行

在 TabActivity 有一个 TabHost，在 TabHost 中有两个选项卡，每个选项卡都有自己的intent。如果一个 tab 改变，在我检测之前，这个 intent 的 onResume()方法被销毁。如何解决这个问题呢？
TabActivity code:

public class TabHostActivity extends TabActivity {    static final int SHOW_SHARE_ACTIVITY = 0;    static final int SHOW_LOGIN_ACTIVITY = 1;    private TabHost tabHost;    private ImageButton composeImageButton;    private SharedPreferences prefs;    private Bundle b;    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.tabhostactivity);               prefs = getSharedPreferences(Constants.PREFS_NAME 0);        //Setup the ActionBar        composeImageButton = (ImageButton) findViewById(R.id.composeImageButton);        composeImageButton.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                if(prefs.getBoolean(""isLoggedIn"" false))                {                    showShareActivity();                }                else                {                    Intent intent = new Intent(TabHostActivity.this LoginActivity.class);                    startActivityForResult(intent SHOW_LOGIN_ACTIVITY);                }            }        });        b = new Bundle();        //Setup the Tabs        Resources res = getResources(); // Resource object to get Drawables        tabHost = getTabHost();  // The activity TabHost        tabHost.setOnTabChangedListener(new OnTabChangeListener() {               @Override              public void onTabChanged(String arg0) {                   if(tabHost.getCurrentTab() == 0) //Check if the Watchlist tab was clicked so we can prompt login                   {                        //Toast toast = Toast.makeText(getApplicationContext()TRENDING = YES"" Toast.LENGTH_SHORT);                        //toast.show();                        b.putBoolean(""isTrendingTab""true);                   }                   else                   {                       Toast toast = Toast.makeText(getApplicationContext()TRENDING = NO"" Toast.LENGTH_SHORT);                       toast.show();                       b.putBoolean(""isTrendingTab""false);                   }              }             });          TabHost.TabSpec spec;  // Resusable TabSpec for each tab        Intent intent;  // Reusable Intent for each tab        // Create an Intent to launch an Activity for the tab (to be reused)        intent = new Intent().setClass(this ARActivity.class);        intent.putExtras(b);        // Initialize a TabSpec for each tab and add it to the TabHost        spec = tabHost.newTabSpec(""trending"").setIndicator(""Trending""res.getDrawable(R.drawable.icon)).setContent(intent);        tabHost.addTab(spec);        // Do the same for the other tabs        intent = new Intent().setClass(this WatchlistActivity.class);        intent.putExtras(b);        spec = tabHost.newTabSpec(""watchlist"").setIndicator(""Watchlist""res.getDrawable(R.drawable.icon)).setContent(intent);        tabHost.addTab(spec);        tabHost.setCurrentTab(0);    }    private void showShareActivity()    {        Intent intent = new Intent(TabHostActivity.this ShareActivity.class);        startActivityForResult(intent SHOW_SHARE_ACTIVITY);    }    protected void onActivityResult(int requestCode int resultCode Intent data) {        if(requestCode == SHOW_LOGIN_ACTIVITY)        {            //Login was successful so lets show the compose box!            if (resultCode == RESULT_OK) {                showShareActivity();            }        }    }}

这是其中一个 activity 中intent里的 onResume 方法：

public void onResume()    {        super.onResume();        Bundle bundle = getIntent().getExtras();        if(bundle.getBoolean(""isTrendingTab""))        {            Toast toast = Toast.makeText(getApplicationContext()TRENDING!"" Toast.LENGTH_SHORT);            toast.show();        }        else        {            Toast toast = Toast.makeText(getApplicationContext()WATCHLIST!"" Toast.LENGTH_SHORT);            toast.show();        }    }

解决方案

你是想在 intent 上输出：b.putBoolean(""isTrendingTab""true); 或者 false。通过检测改变来开启。
这是错误的方法。更改事件总是会发生在活动启动后，你应该做的逻辑也不同。

解决方案二：
不需要使用 onTabChanged()

Intent intent = new Intent(action) // see notes below about ""action""    .setClass(this ARActivity.class)    .putExtra(""isTrendingTab"" true); TabHost.TabSpec spec = tabHost.newTabSpec(""trending"")    .setIndicator(""trending"" getResources().getDrawable(drawableId))    .setContent(intent);tabHost.addTab(spec);

在 onResume()方法中:

if (getIntent().getBooleanExtra(""isTrendingTab"" false)) {...