Activity A (豎屏)
    ↓ 用戶旋轉(zhuǎn)屏幕
onPause() → onStop() → onDestroy()
    ↓ 系統(tǒng)重建
onCreate() → onStart() → onResume()
    → Activity A (橫屏)

public class MainActivity extends AppCompatActivity {
    private String userInput;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        EditText editText = findViewById(R.id.edit_text);
        
        // 恢復(fù)保存的狀態(tài)
        if (savedInstanceState != null) {
            userInput = savedInstanceState.getString("USER_INPUT");
            editText.setText(userInput);
        }
    }

    @Override
    protected void onSaveInstanceState(@NonNull Bundle outState) {
        super.onSaveInstanceState(outState);
        // 保存用戶輸入
        EditText editText = findViewById(R.id.edit_text);
        outState.putString("USER_INPUT", editText.getText().toString());
    }
}

public class MainViewModel extends ViewModel {
    private MutableLiveData<List<String>> dataList = new MutableLiveData<>();

    public LiveData<List<String>> getDataList() {
        return dataList;
    }

    public void loadData() {
        // 模擬耗時(shí)加載
        new Handler().postDelayed(() -> {
            List<String> data = Arrays.asList("Item 1", "Item 2", "Item 3");
            dataList.setValue(data);
        }, 2000);
    }
}

// 在 Activity 中使用
viewModel = new ViewModelProvider(this).get(MainViewModel.class);
viewModel.getDataList().observe(this, list -> {
    // 更新 UI，即使 Activity 重建，數(shù)據(jù)依然存在
    adapter.submitList(list);
});

<activity
    android:name=".MainActivity"
    android:exported="true"
    android:configChanges="orientation|screenSize|keyboardHidden"
    android:exported="true">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

@Override
public void onConfigurationChanged(@NonNull Configuration newConfig) {
    super.onConfigurationChanged(newConfig);

    // 判斷當(dāng)前屏幕方向
    if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
        Toast.makeText(this, "已切換到橫屏", Toast.LENGTH_SHORT).show();
        // 動(dòng)態(tài)調(diào)整 UI
        adjustForLandscape();
    } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
        Toast.makeText(this, "已切換到豎屏", Toast.LENGTH_SHORT).show();
        adjustForPortrait();
    }
}

private void adjustForLandscape() {
    // 橫屏下隱藏某些 View
    findViewById(R.id.ad_banner).setVisibility(View.GONE);
    
    // 調(diào)整 RecyclerView 布局管理器
    RecyclerView recyclerView = findViewById(R.id.recycler_view);
    recyclerView.setLayoutManager(new GridLayoutManager(this, 2));
}

private void adjustForPortrait() {
    // 豎屏下顯示廣告
    findViewById(R.id.ad_banner).setVisibility(View.VISIBLE);
    
    // 恢復(fù)線性布局
    RecyclerView recyclerView = findViewById(R.id.recycler_view);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
}

res/
├── layout/
│   └── activity_main.xml          # 豎屏布局
└── layout-land/
    └── activity_main.xml          # 橫屏布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">

    <!-- 左側(cè)列表 -->
    <fragment
        android:id="@+id/fragment_list"
        android:name="com.example.NewsListFragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1" />

    <!-- 右側(cè)詳情 -->
    <FrameLayout
        android:id="@+id/detail_container"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="2" />

</LinearLayout>

// 在 onConfigurationChanged 中判斷
if (newConfig.keyboardHidden == Configuration.KEYBOARDHIDDEN_NO) {
    // 軟鍵盤彈出
} else if (newConfig.keyboardHidden == Configuration.KEYBOARDHIDDEN_YES) {
    // 軟鍵盤隱藏
}

<!-- 支持多窗口 -->
<activity
    android:name=".MainActivity"
    android:resizeableActivity="true"
    android:supportsPictureInPicture="true"
    android:configChanges="orientation|screenSize|smallestScreenSize">
</activity>

@Composable
fun ResponsiveLayout() {
    val configuration = LocalConfiguration.current
    val isLandscape = configuration.orientation == Configuration.ORIENTATION_LANDSCAPE

    if (isLandscape) {
        Row { /* 橫屏布局 */ }
    } else {
        Column { /* 豎屏布局 */ }
    }
}