Question

我目前正在做一个关于eclipse android开发的教程系列，我正在尝试复制代码以帮助记住所有内容的功能但是我收到onSaveInstanceState（Bundle）的错误，它说“方法onSaveInstanceState（Bundle）是未定义的Object类型“。我已经检查过一切都是确切的多次，但没有发现任何错误。

protected void onSaveInstanceState(Bundle outState)
     {
        super.onSaveInstanceState(outState);

        outState.putDouble(TOTAL_BILL, finalBill);
        outState.putDouble(CURRENT_TIP, tipAmount);
        outState.putDouble(BILL_WITHOUT_TIP, finalBill);
     }

Answer 1

您需要使用@Override并确保您的课程延伸Activity。只要你有这两件事就应该是好的。

class MyActivity extends Activity {

    @Override // May be public depending on the class you are extending
    protected void onSaveInstanceState(Bundle outState) {

        outState.putDouble(TOTAL_BILL, finalBill);
        outState.putDouble(CURRENT_TIP, tipAmount);
        outState.putDouble(BILL_WITHOUT_TIP, finalBill);

        // Wait till after you've added your items to pass the bundle
        super.onSaveInstanceState(outState);
     }
}

根据Activity文档页面，其他扩展Activity的类是 AccountAuthenticatorActivity，ActivityGroup，AliasActivity，ExpandableListActivity，FragmentActivity，ListActivity，NativeActivity，ActionBarActivity，{{ 3}}，LauncherActivity和PreferenceActivity。

如果你想弄清楚某些东西的运作方式，那么Android资源也是一个很好看的地方。很多时候，笔记中有很多关于事物如何实现以及它们依赖的描述。

参考：TabActivity

    /**
     * Called to retrieve per-instance state from an activity before being killed
     * so that the state can be restored in {@link #onCreate} or
     * {@link #onRestoreInstanceState} (the {@link Bundle} populated by this method
     * will be passed to both).
     *
     * <p>This method is called before an activity may be killed so that when it
     * comes back some time in the future it can restore its state.  For example,
     * if activity B is launched in front of activity A, and at some point activity
     * A is killed to reclaim resources, activity A will have a chance to save the
     * current state of its user interface via this method so that when the user
     * returns to activity A, the state of the user interface can be restored
     * via {@link #onCreate} or {@link #onRestoreInstanceState}.
     *
     * <p>Do not confuse this method with activity lifecycle callbacks such as
     * {@link #onPause}, which is always called when an activity is being placed
     * in the background or on its way to destruction, or {@link #onStop} which
     * is called before destruction.  One example of when {@link #onPause} and
     * {@link #onStop} is called and not this method is when a user navigates back
     * from activity B to activity A: there is no need to call {@link #onSaveInstanceState}
     * on B because that particular instance will never be restored, so the
     * system avoids calling it.  An example when {@link #onPause} is called and
     * not {@link #onSaveInstanceState} is when activity B is launched in front of activity A:
     * the system may avoid calling {@link #onSaveInstanceState} on activity A if it isn't
     * killed during the lifetime of B since the state of the user interface of
     * A will stay intact.
     *
     * <p>The default implementation takes care of most of the UI per-instance
     * state for you by calling {@link android.view.View#onSaveInstanceState()} on each
     * view in the hierarchy that has an id, and by saving the id of the currently
     * focused view (all of which is restored by the default implementation of
     * {@link #onRestoreInstanceState}).  If you override this method to save additional
     * information not captured by each individual view, you will likely want to
     * call through to the default implementation, otherwise be prepared to save
     * all of the state of each view yourself.
     *
     * <p>If called, this method will occur before {@link #onStop}.  There are
     * no guarantees about whether it will occur before or after {@link #onPause}.
     * 
     * @param outState Bundle in which to place your saved state.
     * 
     * @see #onCreate
     * @see #onRestoreInstanceState
     * @see #onPause
     */
    protected void onSaveInstanceState(Bundle outState) {
        outState.putBundle(WINDOW_HIERARCHY_TAG, mWindow.saveHierarchyState());
        Parcelable p = mFragments.saveAllState();
        if (p != null) {
            outState.putParcelable(FRAGMENTS_TAG, p);
        }
        getApplication().dispatchActivitySaveInstanceState(this, outState);
    }

Answer 2

将onSaveInstanceState(Bundle outState)方法放在textWatcher方法之外的正确位置只需在分号后面右键，这标志着textWatcher方法的结束。的 [};]

protected void onSaveInstanceState(Bundle outState){ super.onSaveInstanceState(outState); outState.putDouble(Total_Bill, finalBill); outState.putDouble(Tip_Amount, tipamount); outState.putDouble(Bill_Without_Tip, Billbeforetip); }

错误应该消失。

onSaveInstanceState（Bundle）方法未定义

2 个答案: