我个人将Fragment与Activity间的通信比喻为JSP与Servlet间的通信，fragment中用接口的方式来进行与Activity的通信。通信的结果可以作为数据传入另一个Fragment中。当然两个Fragment之间也是可以进行通信的~
注意加载或者切换Fragment时，必须new一个FragmentTransaction对象，不能用同一个FragmentTransaction对象进行对容器进行替换、增加fragment。将fragment填充进容器的方式是（这里分别给两个容器填充了两个fragment对象）：
FragmentManager fragmentManager = getSupportFragmentManager(); FragmentTransaction ft = fragmentManager.beginTransaction(); ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE); ft.add(R.id.container_fragment, new MyFragment()) .commit(); //不能用同个FragmentTransaction来加载两个fragment fragmentManager.beginTransaction() .add(R.id.container_fragment02, new MyFragment02()) .commit();
更换fragment的方式是：
getSupportFragmentManager().beginTransaction(). replace(R.id.container_fragment02, fragment) .addToBackStack(null) .commit();
本实例完成的是点击一个Fragment中的按钮后，fragment给activity传值，activity接受到值后给另一个fragment（右边的）传值，以此改变textview中的内容。
activity_main.xml （定义了2个布局来作为fragment的容器）
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#000000" android:orientation="horizontal" > <FrameLayout android:id="@+id/container_fragment" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_weight="1" android:background="#ffffff" android:layout_marginRight="1dp" /> <FrameLayout android:id="@+id/container_fragment02" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_weight="1" android:background="#ffffff" android:layout_marginLeft="1dp" > </FrameLayout> </LinearLayout>
fragment.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="${relativePackage}.${activityClass}" > <Button android:id="@+id/fragment_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerVertical="true" android:layout_marginBottom="41dp" android:text="kale" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_above="@+id/fragment_button" android:layout_centerHorizontal="true" android:layout_marginBottom="46dp" android:text="点击后传值" android:textAppearance="?android:attr/textAppearanceLarge" /> </RelativeLayout>
MyFragment
package com.kale.activity; import android.app.Activity; import android.os.Bundle; import android.support.annotation.Nullable; import android.support.v4.app.Fragment; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.View.OnClickListener; import android.widget.Button; public class MyFragment extends Fragment{ private MyCallback mCallback; //定义一个调用接口} public interface MyCallback { public void onBtnClick(View v); } String TAG = getClass().getName(); @Override public void onAttach(Activity activity) { super.onAttach(activity); Log.e(TAG, "F------------onAttach->"); if(!(activity instanceof MyCallback)) { throw new IllegalStateException("fragment所在的Activity必须实现Callbacks接口"); } //把绑定的activity当成callback对象 mCallback = (MyCallback)activity; } @Override public void onActivityCreated(@Nullable Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); Log.e(TAG, "F------------onActivityCreated->"); //一定要在定义好视图后才来初始化控件，不能放在onCreat()里面 Button btn = (Button)getActivity().findViewById(R.id.fragment_button); btn.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { mCallback.onBtnClick(v); } }); } @Override public void onDetach() { super.onDetach(); Log.e(TAG, "F------------onDetach->"); mCallback = null;//移除前幅值为空 } }
fragment02.xml
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:id="@+id/fragment_textView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerVertical="true" android:text="null" android:textAppearance="?android:attr/textAppearanceLarge" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_above="@+id/fragment_textView" android:layout_centerHorizontal="true" android:layout_marginBottom="40dp" android:textAppearance="?android:attr/textAppearanceLarge" android:text="传来的信息" /> </RelativeLayout>
MyFragment02
package com.kale.activity; import android.app.Activity; import android.os.Bundle; import android.support.annotation.Nullable; import android.support.v4.app.Fragment; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; public class MyFragment02 extends Fragment{ public static final String KEY = "key"; String TAG = getClass().getName(); @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { Log.e(TAG, "F------------onCreateView->"); return inflater.inflate(R.layout.fragment02, container, false); } @Override public void onActivityCreated(@Nullable Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); Log.e(TAG, "F------------onActivityCreated->"); //一定要在定义好视图后才来初始化控件，不能放在onCreat()里面 TextView tv = (TextView)getActivity().findViewById(R.id.fragment_textView); tv.setText("haha"); Bundle bundle = getArguments(); if (bundle == null) { tv.setText("默认值01"); } else { tv.setText(bundle.getString(KEY, "默认值02")); } } }
MainActivity
package com.kale.activity; import android.os.Bundle; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentTransaction; import android.support.v7.app.ActionBarActivity; import android.util.Log; import android.view.View; import android.widget.Button; import com.kale.activity.MyFragment.MyCallback; public class MainActivity extends ActionBarActivity implements MyCallback{ String TAG = getClass().getName(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Log.e(TAG, "------------onCreate------------"); FragmentManager fragmentManager = getSupportFragmentManager(); FragmentTransaction ft = fragmentManager.beginTransaction(); ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE); ft.add(R.id.container_fragment, new MyFragment()) .commit(); //不能用同个FragmentTransaction来加载两个fragment fragmentManager.beginTransaction() .add(R.id.container_fragment02, new MyFragment02()) .commit(); } @Override protected void onStart() { super.onStart(); Log.e(TAG, "------------onStart------------"); } @Override protected void onRestart() { super.onRestart(); Log.e(TAG, "------------onRestart------------"); } @Override protected void onResume() { super.onResume(); Log.e(TAG, "------------onResume------------"); } @Override protected void onPause() { super.onPause(); Log.e(TAG, "------------onPause------------"); } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); Log.e(TAG, "------------onSaveInstanceState------------"); } @Override protected void onStop() { super.onStop(); Log.e(TAG, "------------onStop------------"); } @Override protected void onDestroy() { super.onDestroy(); Log.e(TAG, "------------onDestroy------------"); } @Override protected void onRestoreInstanceState(Bundle savedInstanceState) { super.onRestoreInstanceState(savedInstanceState); Log.e(TAG, "------------onRestoreInstanceState------------"); } @Override public void onBtnClick(View v) { Button btn = (Button)v; Log.i(TAG, btn.getText()+""); Bundle bundle = new Bundle(); bundle.putString(MyFragment02.KEY, btn.getText()+""); MyFragment02 fragment = new MyFragment02(); fragment.setArguments(bundle); getSupportFragmentManager().beginTransaction(). replace(R.id.container_fragment02, fragment) .addToBackStack(null) .commit(); } }