Fragment向Activity傳遞值

一.Fragment向Activity傳值的步驟 接口回調傳遞(5部曲)

• fragment中准備回調接口 接口中聲明傳值的回調方法

• 在fragment中定義屬性private MyListener myListener

• 重寫fragment中的onAttach()方法
  listener = (MyLisener)getActivity();

• fragment觸發事件時回傳值

• Activity中實現回調接口 重寫回調方法獲取回傳的值並顯示

  import android.app.Activity;
  import android.app.FragmentManager;
  import android.app.FragmentTransaction;
  import android.os.Bundle;
  import android.widget.TextView;
  import android.widget.Toast;
  
  public class MainActivity extends Activity implements MyListener{
      private TextView textView;  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          textView = (TextView) findViewById(R.id.textView);
          FragmentManager manager = getFragmentManager();
          FragmentTransaction transaction = manager.beginTransaction();
          transaction.add(R.id.layout_container_fragment, new MyFragment());
          transaction.commit();        
      }
  
      @Override
      public void sendContent(String info) {
          if (info!=null && !"".equals(info)) {
              textView.setText(info);
          }else {
              Toast.makeText(MainActivity.this, "請輸入內容", Toast.LENGTH_SHORT).show();
          }
      }
  }

  import android.app.Activity;
  import android.app.Fragment;
  import android.os.Bundle;
  import android.view.LayoutInflater;
  import android.view.View;
  import android.view.View.OnClickListener;
  import android.view.ViewGroup;
  import android.widget.Button;
  import android.widget.EditText;
  
  public class MyFragment extends Fragment {
      private EditText editText;
      private Button button;  
      private MyListener myListener;//②作為屬性定義 
      //①定義回調接口
      public interface MyListener{
          public void sendContent(String info);
      }
      
      @Override
      public void onAttach(Activity activity) {
          super.onAttach(activity);
          myListener = (MyListener) getActivity();
      }
      
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
              Bundle savedInstanceState) {
          View view = inflater.inflate(R.layout.layout_fragment, container, false);
          editText = (EditText) view.findViewById(R.id.editText1);
          button = (Button) view.findViewById(R.id.button1);
          
          //點擊按鈕時需要將EditText中的值取出來傳給宿主Activity
          button.setOnClickListener(new OnClickListener() {
              
              @Override
              public void onClick(View v) {
                  String value = editText.getText().toString();
                  myListener.sendContent(value);//將內容進行回傳
              }
          });
          return view;
      }
  }