文章预览

• 前言
• 一、示例
• • 1.1、activity_main.xml
  • 1.2、创建接口IFragmentCallback .java
  • 1.3、创建Fragment
  • • 1.3.1、BlankFragment1.java
    • 1.3.2、fragment_blank1.xml
  • 1.4、MainActivity.java
• 二、测试

前言

参考文章
https://www.jianshu.com/p/825eb1f98c19
https://www.jianshu.com/p/ab49f4a13a56
https://blog.csdn.net/dingfengen/article/details/51261904

一、示例

1.1、activity_main.xml

<?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="vertical"
    tools:context=".MainActivity">

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btn"
        android:text="@string/change"></Button>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btn_2"
        android:text="@string/replace"></Button>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/framelayout"
        android:background="@color/colorAccent"></FrameLayout>

</LinearLayout>

1.2、创建接口IFragmentCallback .java

package com.example.fragmentmanagers;

public interface IFragmentCallback {
    void sendMsgToActivity(String msg);
    String getMsgFromActivity(String msg);
}

1.3、创建Fragment

1.3.1、BlankFragment1.java

package com.example.fragmentmanagers;

import android.content.Context;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;

/**
 * A simple {@link Fragment} subclass.
 * Use the {@link BlankFragment1#newInstance} factory method to
 * create an instance of this fragment.
 */
public class BlankFragment1 extends Fragment {
    private static final String TAG = "BlankFragment1";
    private View rootview;


    public BlankFragment1() {
        // Required empty public constructor
    }

    /**
     * 通过接口与Activity通信
     */
    private IFragmentCallback fragmentCallback;
    public void setFragmentCallback(IFragmentCallback callback){
        fragmentCallback = callback;
    }

    @Override
    public void onAttach(@NonNull Context context) {
        super.onAttach(context);
        Log.d(TAG, "onAttach: ");
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        if (rootview == null){
            rootview = inflater.inflate(R.layout.fragment_blank1, container, false);
        }
        Button btn = rootview.findViewById(R.id.btn_3);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
//                fragmentCallback.sendMsgToActivity("hello, I'm from Fragment");//给Activity通信
                String msg = fragmentCallback.getMsgFromActivity("null");
                Toast.makeText(BlankFragment1.this.getContext(), msg, Toast.LENGTH_SHORT).show();
            }
        });
        Log.d(TAG, "onCreateView: ");
        return rootview;
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        Log.d(TAG, "onActivityCreated: ");
    }

}

1.3.2、fragment_blank1.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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=".BlankFragment1">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment" />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:id="@+id/btn_3"
        android:text="数据传递"/>

</FrameLayout>

1.4、MainActivity.java

package com.example.fragmentmanagers;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import java.io.BufferedOutputStream;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = findViewById(R.id.btn);
        button.setOnClickListener(this);
        Button button2 = findViewById(R.id.btn_2);
        button2.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.btn:
                BlankFragment1 bf = new BlankFragment1();
                bf.setFragmentCallback(new IFragmentCallback() {
                    @Override
                    public void sendMsgToActivity(String msg) {
                        Toast.makeText(MainActivity.this,msg, Toast.LENGTH_LONG).show();
                    }

                    @Override
                    public String getMsgFromActivity(String msg) {
                        return "Activity给Fragement通信";
                    }
                });

                replaceFragment(bf);
                break;
            case R.id.btn_2:
                replaceFragment(new ItemFragment() );

        }
    }

    // 动态切换fragment
    private void replaceFragment(Fragment fragment) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction transation = fragmentManager.beginTransaction();
        transation.replace(R.id.framelayout, fragment);
        //添加这个表示用了栈
        transation.addToBackStack(null);
        transation.commit();
    }
}

二、测试