如何在 Android 中的 Fragment 之間傳遞值?
此示例演示瞭如何在 Android 中在 Fragment 之間傳遞值。
步驟 1 - 在 Android Studio 中建立一個新專案,轉到檔案 ⇒ 新建專案,並填寫所有必需的詳細資訊以建立新專案。
步驟 2 - 將以下程式碼新增到 res/layout/activity_main.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" android:background="#574706" tools:context=".MainActivity"> <fragment android:layout_width="wrap_content" android:layout_height="wrap_content" android:name="app.com.sample.FragmentOne" android:id="@+id/fragment" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" tools:layout="@layout/fragment_fragment_one" /> <fragment android:layout_width="wrap_content" android:layout_height="wrap_content" android:name="app.com.sample.FragmentTwo" android:id="@+id/fragment2" android:layout_below="@+id/fragment" android:layout_centerHorizontal="true" android:layout_marginTop="41dp" tools:layout="@layout/fragment_fragment_two" /> </RelativeLayout>
步驟 3 - 將以下程式碼新增到 src/MainActivity.java
import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; public class MainActivity extends AppCompatActivity implements FragmentOne.OnFragmentInteractionListener{ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.menu_main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { int id = item.getItemId(); if (id == R.id.textUpdate) { return true; } return super.onOptionsItemSelected(item); } @Override public void onFragmentInteraction(String userContent) { FragmentTwo fragmentTwo = (FragmentTwo) getSupportFragmentManager().findFragmentById(R.id.fragment2); fragmentTwo.updateTextField(userContent); } }
步驟 4 - 建立兩個 Fragment(FragmentOne 和 FragmentTwo)並新增以下程式碼 -
a) FragmentOne.java
import android.app.Activity; import android.os.Bundle; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; public class FragmentOne extends Fragment { private OnFragmentInteractionListener mListener; private EditText userInput; private String userData; public FragmentOne() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_fragment_one, container, false); userInput = view.findViewById(R.id.userInput); Button update = view.findViewById(R.id.button); update.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { if(userInput.getText().toString().equals("")){ Toast.makeText(getActivity(), "User input value must be filled", Toast.LENGTH_LONG).show(); return; } userData = userInput.getText().toString(); onButtonPressed(userData); } }); return view; } public void onButtonPressed(String userContent) { if (mListener != null) { mListener.onFragmentInteraction(userContent); } } @Override public void onAttach(Activity activity) { super.onAttach(activity); try { mListener = (OnFragmentInteractionListener) activity; } catch (ClassCastException e) { throw new ClassCastException(activity.toString() + " must implement OnFragmentInteractionListener"); } } @Override public void onDetach() { super.onDetach(); mListener = null; } public interface OnFragmentInteractionListener { void onFragmentInteraction(String userContent); } }
fragment_fragment_one.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" android:padding="4dp" android:paddingBottom="32dp"> <EditText android:id="@+id/userInput" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:layout_marginTop="16dp" android:ems="10" android:inputType="text"> <requestFocus /> </EditText> <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_below="@id/userInput" android:layout_marginTop="20dp" android:padding="16dp" android:elevation="4dp" android:text="Update" /> </RelativeLayout>
b) FragmentTwo.java
import android.os.Bundle; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; public class FragmentTwo extends Fragment { private TextView updateText; public FragmentTwo() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_fragment_two, container, false); updateText = view.findViewById(R.id.textUpdate); return view; } public void updateTextField(String newText){ updateText.setText(newText); } }
fragment_fragment_two -
<?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/textUpdate" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="" android:textSize="24sp" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:textStyle="bold" android:layout_marginTop="32dp" /> </RelativeLayout>
步驟 5 - 將以下程式碼新增到 androidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.sample"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
讓我們嘗試執行您的應用程式。我假設您已將您的實際 Android 移動裝置連線到您的計算機。要從 Android Studio 執行應用程式,請開啟您的專案之一的活動檔案,然後單擊工具欄中的執行 圖示。選擇您的移動裝置作為選項,然後檢查您的移動裝置,它將顯示您的預設螢幕 -
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