Activity与Fragment通信，Fragment之间互相通信
效果显现：
实现步骤：
1.创建MainActivity，FragmentA，FragmnetB在activity_main.xml中静态加载FragmentA，FragmnetB
2.在MainActivity中获取FragmentA对象，再用对象，调用FragmentA中的方法，实现Activity与Fragment通信之间的通信
3.在FragmentA中获取MainActivity的对象，在通过MainActivity的对象获取FragmnetB对象，最后调用FragmnetB中方法，实现Fragment之间互相通信。
代码实现：
1.创建FragmentA，FragmnetB和相应的布局，这里我就不多解释了：
1.a_fragment.xml：
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<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#d41313"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="25sp"
android:background="#000"
android:textColor="#fff"
android:text=" this is a fragent"
android:gravity="center"/>
<TextView
android:id="@+id/a_frag_tv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="25sp"
android:text="show text"
android:gravity="center"/>
<EditText
android:id="@+id/a_frag_et"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<Button
android:id="@+id/a_frag_btn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAllCaps="false"
android:text="send to FragmentB"/>
</LinearLayout>
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2.FragmentA：
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public class FragmentA extends Fragment {
private TextView showTv;
private EditText toBEt;
private Button toBBtn;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.a_fragment, container, false);
bindID(view);
return view;
}
private void bindID(View view) {
showTv = view.findViewById(R.id.a_frag_tv);
toBEt = view.findViewById(R.id.a_frag_et);
toBBtn = view.findViewById(R.id.a_frag_btn);
}
}
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3.b_fragment.xml：
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:background="#3dd526"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="this is b fragment"
android:textColor="#fff"
android:background="#000"
android:textSize="25sp"/>
<TextView
android:id="@+id/b_frag_tv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="show text"
android:textSize="25sp"/>
</LinearLayout>
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4.FragmentB：
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public class FragmentB extends Fragment {
private TextView showTv;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.b_fragment,container,false);
showTv = view.findViewById(R.id.b_frag_tv);
return view;
}
}
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2.在activity_main.xml中加载之前的两个碎片：
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
tools:context="com.example.communicationfragment.MainActivity">
<LinearLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_weight="1">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="25sp"
android:background="#000"
android:textColor="#fff"
android:text=" this is Activity"
android:gravity="center"/>
<EditText
android:id="@+id/main_to_a_et"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<Button
android:id="@+id/main_to_a_btn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAllCaps="false"
android:text="send to FragmentA"/>
</LinearLayout>
<FrameLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1">
<fragment
android:id="@+id/fragment_a"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:name="com.example.communicationfragment.FragmentA"/>
</FrameLayout>
<FrameLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1">
<fragment
android:id="@+id/fragment_b"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:name="com.example.communicationfragment.FragmentB"/>
</FrameLayout>
</LinearLayout>
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3.好了，做了这么多的准备工作，现在可以实现功能了，首先实现Activity与Fragment通信，修改FragmentA中的代码，添加一个方法：
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public class FragmentA extends Fragment {
...........
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
...............
private void bindID(View view) {
............
}
//创建公共地自定义方法，以便被调用
public void reFresh(String content) {
//通过传过来的参数，改变控件值
showTv.setText(content);
}
}
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4.修改MainActivity中的代码，就可以实现Activity与Fragmnet之间的通讯了：
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public class MainActivity extends AppCompatActivity {
..........
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bindID();
//对发送按钮进行监听
toABtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//获取输入内容
String content = toAEt.getText().toString();
//通过getSupportFragmentManager().findFragmentById（）获取FragmentA对象
FragmentA fragmentA = (FragmentA) getSupportFragmentManager().findFragmentById(R.id.fragment_a);
//调用reFresh（）方法
fragmentA.reFresh(content);
}
});
}
private void bindID() {
..........
}
}
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5.下面我们来实现Fragment之间互相通信，在FragmentB中条件语句：
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public class FragmentB extends Fragment {
private TextView showTv;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
...................
}
public void reFresh(String content){
showTv.setText(content);
}
}
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6.最后在FragmentA中添加语句：
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public class FragmentA extends Fragment {
private TextView showTv;
private EditText toBEt;
private Button toBBtn;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
..............
toBBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String content = toBEt.getText().toString();
//获取当前activity的对象
MainActivity mainActivity = (MainActivity) getActivity();
//通过activity的对象调用getSupportFragmentManager().findFragmentById（）方法获取fragmentB对象
FragmentB fragmentB = (FragmentB) mainActivity.getSupportFragmentManager().findFragmentById(R.id.fragment_b);
fragmentB.reFresh(content);
}
});
return view;
}
private void bindID(View view) {
..........
}
public void reFresh(String content) {
.........
}
}
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