Android Activity與Fragment之間的跳轉實例詳解

Activity及Fragment之間的跳轉

直接跳轉

基本使用方法

public class MainActivity extends AppCompatActivity {

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

  public void jump(View view) {
    Intent intent = new Intent(this, VideoPlayActivity.class);
    intent.putExtra("video_id", "1");
    startActivity(intent);
  }
}

public class VideoPlayActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_video_play);

    Intent intent = getIntent();
  }
}

借助工具類

然而並沒什麼卵用

public static void startActivity(Context context, Class clazz,Bundle data) {
  Intent intent = new Intent(context, clazz);
  if(data != null){
    intent.putExtras(data);
  }
  context.startActivity(intent);
}

推薦方案

1. 把new Intent()放在目標Activity,這樣可以onCreate裡的getIntent形成對應
2. 更容易理解和管理一個出口，多個入口的情況
3. 較方便維護傳遞數據的key和value（即key由目標Activity來定義，value是實際的來源）

public class MainActivity extends AppCompatActivity {

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

  public void jump(View view) {
    startActivity(VideoPlayActivity.newIntent(this, "1"));
  }

}

public class VideoPlayActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_video_play);

  }

  public static Intent newIntent(Context context, String vid) {
    Intent intent = new Intent(context, VideoPlayActivity.class);
    intent.putExtra("video_id", vid);
    return intent;
  }
}

Fragment跳轉

• 首先需要一個空的構造方法，Fragment恢復重建要使用。
• 使用newInstance代替構造方法傳參
• 在Fragment.onCreate方法獲取實參
  

public class MainFragment{

  public MainFragment() {
    // Required empty public constructor
  }

  public static MainFragment newInstance(int pos) {
    MainFragment fragment = new MainFragment();
    Bundle args = new Bundle();
    args.putInt("pos", pos);
    fragment.setArguments(args);
    return fragment;
  }

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getArguments() != null) {
      pos = getArguments().getInt("pos");
    }
  }
}

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