Fragment與Activity間的通信

Activity向Fragment傳值

Activity向引入的Fragment傳值步驟：
1.Activity中創建Fragment對象，調用setArguments(bundle)方法儲存值
2.Fragment中調用getArguments()獲取傳遞的bundle對象解析獲取具體值

示例代碼

MainActivity.java

package com.example.activitytofragment;

import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

    private EditText et_content;
    private FragmentManager manager;
    private FragmentTransaction transaction;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        et_content = findViewById(R.id.et_content);
        manager = getFragmentManager();
        transaction = manager.beginTransaction();
        transaction.add(R.id.ll_content,new ResultFragment());
        transaction.commit();
    }

    /**
     * 點擊按鈕將EditText中輸入的文本傳入ResultFragment中
     */
    public void sendValue(View view){
        // 獲取輸入的文本信息
        String info = et_content.getText().toString().trim();
        ResultFragment fragment = new ResultFragment();
        // 創建Bundle對象，把需要傳遞的數據存到bundle裏，然後調用fragment的setArguments()方法傳遞bundle
        Bundle bundle = new Bundle();
        bundle.putString("to",info);
        fragment.setArguments(bundle);
        // 開啓事務
        transaction = manager.beginTransaction();
        // 替換之前沒有數據的Fragment
        transaction.replace(R.id.ll_content,fragment);
        // 提交事務
        transaction.commit();
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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="com.example.activitytofragment.MainActivity">

    <EditText
        android:id="@+id/et_content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/et_content" />

    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="點擊傳值"
        android:layout_centerInParent="true"
        android:gravity="center"
        android:layout_below="@id/et_content"
        android:onClick="sendValue"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:layout_below="@id/btn"
        android:id="@+id/ll_content">

    </LinearLayout>


</RelativeLayout>

ResultFragment.java

package com.example.activitytofragment;

import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


public class ResultFragment extends Fragment {

    private TextView tv_content;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_layout, null);
        tv_content = view.findViewById(R.id.tv_content);
        // 先調用getArguments()方法獲取bundle  bundle對象中根據key獲取傳遞的數據，再展示到TextView中
        Bundle bundle = getArguments();
        if (bundle != null) {
            String info = bundle.getString("to");
            tv_content.setText(info);
        }
        return view;
    }
}

fragment_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv_content"
        android:textSize="30sp"
        android:gravity="center"/>
</android.support.constraint.ConstraintLayout>

效果圖

Fragment向Activity傳值

Fragment向所在Activity傳值步驟：
1.Fragment中定義傳值的回調接口，在生命週期onAttach()或者onCreate()方法中獲取接口的實現
2.Fragment需要傳值的位置調用接口回調方法傳值
3.Activity實現回調接口重寫回調方法獲取傳遞的值
代碼示例：
MainActivity.java

package com.example.fragmenttoactivity;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements ResourceFragment.MyListener{

    private TextView tv_show;

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

    @Override
    public void sendMessage(String str) {
        // 判斷不等於空也不等於雙引號空格
        if (str!=null&&!"".equals(str)){
            // 回傳數據進行展示
            tv_show.setText(str);
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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="com.example.fragmenttoactivity.MainActivity">

    <TextView
        android:id="@+id/tv_show"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="30sp" />

    <fragment
        android:id="@+id/fragment_resource"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/tv_show"
        android:name="com.example.fragmenttoactivity.ResourceFragment"/>

</RelativeLayout>

ResourceFragment.java

package com.example.fragmenttoactivity;

import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;


public class ResourceFragment extends Fragment {

    private EditText et_content;
    private Button button;
    private MyListener listener;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 實例話MyListener，因爲Activity實現了MyListener，所以就是他的子類
        listener = (MyListener) getActivity();

    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_resource,null);
        et_content = view.findViewById(R.id.et_content);
        button = view.findViewById(R.id.btn);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 獲取EditText中的值
                String info = et_content.getText().toString().trim();
                // 接口回傳的形式回傳數據
                listener.sendMessage(info);
            }
        });
        return view;
    }

    // 定義接口 接口中定義回傳數據的方法
    public interface MyListener{
        public abstract void sendMessage(String str);
    }
}

fragment_resource.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">

    <EditText
        android:id="@+id/et_content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/et_content" />

    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/et_content"
        android:layout_centerHorizontal="true"
        android:gravity="center"
        android:text="@string/btn" />

</RelativeLayout>

效果圖

同一個Activity下的Fragment與Fragment之間的傳值

同一個Activity中不同Fragment之間的傳值有三種方法：
方法一：先得到FragmentManager，再調用findFragmentById()方法，根據id獲取到Fragment對象，調用fragment中的setTextView()方法賦值
方式二：先調用getFragmentManager()獲得FragmentManager對象，然後調用findFragmentById()方法獲得右側的Fragment對象，再調用getView()獲得右側的fragment的view對象，最後調用view的findViewById()方法獲得需要賦值的控件
方式三：先調用getActivity()獲取所屬Activity的對象，再通過activity的findViewById()獲取目標控件
代碼示例
MainActivity.java

package com.example.fragmenttofragment;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

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

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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:orientation="horizontal"
    tools:context="com.example.fragmenttofragment.MainActivity">

    <fragment
        android:id="@+id/fragment_left"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:name="com.example.fragmenttofragment.LeftFragment"
        android:layout_weight="1" />

    <fragment
        android:id="@+id/fragment_right"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:name="com.example.fragmenttofragment.RightFragment"
        android:layout_weight="1" />
</LinearLayout>

LeftFragment.java

package com.example.fragmenttofragment;

import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;


public class LeftFragment extends Fragment {

    private EditText et_content;
    private Button btn_send;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_left,null);
        et_content = view.findViewById(R.id.et_content);
        btn_send = view.findViewById(R.id.btn_send);
        btn_send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String info = et_content.getText().toString().trim();   // 獲取輸入的內容
/*                // 方式一：先得到FragmentManager，再調用findFragmentById()方法，根據id獲取到Fragment對象，調用fragment中的setTextView()方法賦值
                RightFragment rightFragmenet = (RightFragment) getFragmentManager().findFragmentById(R.id.fragment_right);
                rightFragmenet.setTextView(info);*/

/*                // 方式二：先調用getFragmentManager()獲得FragmentManager對象，然後調用findFragmentById()方法獲得右側的Fragment對象，
                //         再調用getView()獲得右側的fragment的view對象，最後調用view的findViewById()方法獲得需要賦值的控件
                TextView tv_show = getFragmentManager().findFragmentById(R.id.fragment_right)
                        .getView().findViewById(R.id.tv_show);
                tv_show.setText(info);*/

                // 方式三：先調用getActivity()獲取所屬Activity的對象，再通過activity的findViewById()獲取目標控件
                TextView tv_show = getActivity().findViewById(R.id.tv_show);
                tv_show.setText(info);

            }
        });
        return view;
    }
}

fragment_left.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">

    <EditText
        android:id="@+id/et_content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:hint="@string/et_content" />

    <Button
        android:id="@+id/btn_send"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/et_content"
        android:layout_centerHorizontal="true"
        android:gravity="center"
        android:text="@string/btn_send" />

</RelativeLayout>

RightFragment.java

package com.example.fragmenttofragment;

import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class RightFragment extends Fragment {

    private TextView tv_show;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_right,null);
        tv_show = view.findViewById(R.id.tv_show);
        return view;
    }

    // 定義一個方法給TextView賦值
    public void setTextView(String text){
        tv_show.setText(text);
    }
}

fragment_right.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/tv_show"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:textSize="30sp" />

</RelativeLayout>

效果圖

Fragment與Activity間的通信 Fragment與Fragment間的通信

Fragment與Activity間的通信

Activity向Fragment傳值

示例代碼

效果圖

Fragment向Activity傳值

同一個Activity下的Fragment與Fragment之間的傳值

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