Fragment高级进阶

Fragment高级进阶
Fragment 回退栈
Fragment 传值介绍
activity 给 fragment传值
fragment 给 activity传值
Activity中的代码
Activity中的xml文件
fragment中的代码
fragment的xml文件
fragment 给 fragment 传值
fragment 多层嵌套
Fragment 回退栈
代码演示:

注意fragment的生命周期.

 radioGroupId.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                switch (checkedId) {
                    case R.id.person_id:
                        manager = getSupportFragmentManager();
                        fragmentTransaction = manager.beginTransaction();
//                        fragmentTransaction.replace(R.id.frame_layout_id,new FristFragment());
                        fragmentTransaction.add(R.id.frame_layout_id,new FristFragment());
						//入栈
                        fragmentTransaction.addToBackStack("11");
                        fragmentTransaction.commit();
                        break;
                    case R.id.message_id:
                        manager = getSupportFragmentManager();
						
						//出栈
                        manager.popBackStack(); 
                        SelectActivity.this.fragmentTransaction = manager.beginTransaction();
                        SelectActivity.this.fragmentTransaction.replace(R.id.frame_layout_id,new SecondFragment());
//                        fragmentTransaction.addToBackStack(null);
                        SelectActivity.this.fragmentTransaction.commit();
                        break;

                    default:
                        break;
                }
            }
        });

 	case R.id.message_id:
    manager = getSupportFragmentManager();
//  manager.popBackStack();
    fragmentTransaction = manager.beginTransaction();
    fragmentTransaction.replace(R.id.frame_layout_id,new SecondFragment());
    //添加了返回栈,点击back的时候,不会退出activity,而会返回到之前的fragment界面.
//  fragmentTransaction.addToBackStack(null);
    fragmentTransaction.commit();
     break;

Fragment 传值介绍

不同页面间传值是最基本的要求.(这是页面间的联动,交互)

请看需求

activity 给 fragment传值

主要涉及到一个方法是getArguments()和setArguments().
一个设置属性值,一个去取属性值.

步骤：
要传的值，放到bundle对象里；
在Activity中创建该Fragment的对象fragment，通过调用
fragment.setArguments()传递到fragment中；
然后更新fragment.
在该Fragment中通过调用getArguments()得到bundle对象，就能得到里面的值。

代码来了 这是刚创建完成的activity

package com.example.day004;

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

/**
 * activity 向 fragment 传值
 */
public class A2FActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_a_2_f);
    }

	//点击事件的方法
	public void click(View view) {
	}
}

这是修完以后的他的xml的布局文件

<?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=".A2FActivity">

    <EditText
        android:id="@+id/et_id"
        android:hint="来啊,传点啥吧!"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

   <!--在activity中定义了点击事件-->
    <Button
        android:id="@+id/button_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="点我试试"
        android:onClick="click"
        />

    <!--用来显示内容的,是个容器,里面可以放fragment-->
    <LinearLayout
        android:orientation="horizontal"
        android:id="@+id/linear_layout_id"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </LinearLayout>

</LinearLayout>

创建fragment(右键一键完事,带布局)

package com.example.day004.fragment;


import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.example.day004.R;

/**
  *用来接受传值的
 */
public class ShowContextFragment extends Fragment {
    
    public ShowContextFragment() {
        // Required empty public constructor
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_show_context, container, false);
    }
}

修改后的fragment的xml布局文件

<?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=".fragment.ShowContextFragment">
    
    <!--只加了一个Id,其他可有可无-->
    <TextView
        android:id="@+id/context_tv_id"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:textColor="@color/colorAccent"
        android:textSize="30sp"
        android:text="@string/hello_blank_fragment" />

</FrameLayout>

完整版的fragment

package com.example.day004.fragment;


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;

import com.example.day004.R;

/**
 *用来接受传值的
 */
public class ShowContextFragment extends Fragment {

    private TextView textView;
    public ShowContextFragment() {
        // Required empty public constructor
    }
    //现在text里面的值是"hello_blank_fragment",思路就是拿到控件,重新赋值即可.
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View inflate = inflater.inflate(R.layout.fragment_show_context, container, false);
        //1 拿控件
        textView = inflate.findViewById(R.id.context_tv_id);
        //2 给控件赋值
        Bundle arguments = getArguments();
        if(arguments != null){ //第一次启动一定为null,所以要判断一下
            String key = arguments.getString("key");
            textView.setText(key);
        }
        return inflate;
    }

}

完整版的a2fActivity

package com.example.day004;

import android.icu.util.BuddhistCalendar;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

import com.example.day004.fragment.ShowContextFragment;

import java.io.BufferedReader;

/**
 * activity 向 fragment 传值
 */
public class A2FActivity extends AppCompatActivity {
    private FragmentManager fragmentManager;
    private FragmentTransaction fragmentTransaction;
    private EditText editText;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_a_2_f);

        //0,取到edit的控件和值
        editText =  findViewById(R.id.et_id);

        //1,在这里动态添加一个fragment
        fragmentManager = getSupportFragmentManager();
        fragmentTransaction = fragmentManager.beginTransaction();
        //注意这个布局文件,是R.layout.activity_a_2_f xml文件里的线性布局
        fragmentTransaction.add(R.id.linear_layout_id,new ShowContextFragment());
        fragmentTransaction.commit();
    }

    public void click(View view) {
        //取到输入的值
        String string = editText.getText().toString();
        //创建fragment对象
        ShowContextFragment showContextFragment = new ShowContextFragment();
        //创建bundle
        Bundle bundle = new Bundle();
        bundle.putString("key",string);
        //给fragment对象赋值
        showContextFragment.setArguments(bundle);

        //动态修改fragment
        fragmentManager = getSupportFragmentManager();
        fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.linear_layout_id,showContextFragment);
        fragmentTransaction.commit();
    }
}

fragment 给 activity传值
第一种：
在Activity中调用getFragmentManager()得到fragmentManager,，调用findFragmentByTag(tag)或者通过findFragmentById(id)
FragmentManager fragmentManager = getFragmentManager()；
Fragment fragment = fragmentManager.findFragmentByTag(tag)；

第二种：
通过回调的方式，定义一个接口（可以在Fragment类中定义），接口中有一个空的方法，在fragment中需要的时候调用接口的方法，值可以作为参数放在这个方法中，然后让Activity实现这个接口，必然会重写这个方法，这样值就传到了Activity中.
大白话,就是java的父类引用指向了子类对象

按钮在fragment中.赖的重新画图了.谢谢.

Activity中的代码

package com.example.day004;

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

import com.example.day004.fragment.ShowTitleFragment;

public class F2AActivity extends AppCompatActivity implements ShowTitleFragment.MyListener {

    private TextView textView;
    @Override
    public void sendMessage(String string) {
        textView.setText(string);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_f_2_a);
        textView = findViewById(R.id.f2a_tv_id);
    }
}

Activity中的xml文件

<?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:orientation="vertical"
    android:layout_height="match_parent"
    tools:context=".F2AActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/f2a_tv_id"
        android:textSize="30sp"
        android:hint="提示而已"
        />

    <fragment
        android:name="com.example.day004.fragment.ShowTitleFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/f2a_fm_id">

    </fragment>

</LinearLayout>

fragment中的代码

package com.example.day004.fragment;


import android.content.Context;
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 com.example.day004.R;

/**
 * A simple {@link Fragment} subclass.
 */
public class ShowTitleFragment extends Fragment {

    private EditText editText;
    private Button button;

    private MyListener listener;

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

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        //拿到与当前fragment关联的Activity.
        listener = (MyListener) getActivity(); 
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View inflate = inflater.inflate(R.layout.fragment_show_title, container, false);

       //取到所有控件
        editText = inflate.findViewById(R.id.fm_title_et_id);
        button = inflate.findViewById(R.id.fm_title_button_id);
        //点击事件
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String string = editText.getText().toString();
                if(string != null){
                    //注意了.这里是父类引用指向了子类对象,其实是activity中的sendmessage方法在执行.
                    listener.sendMessage(string);
                }
            }
        });
		//返回fragment中的布局视图
        return inflate;
    }

   //自定义的接口
    public interface MyListener{
        void sendMessage(String string);
    }

}

fragment的xml文件

<?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="vertical"
    tools:context=".fragment.ShowTitleFragment">
    
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/fm_title_et_id"
        android:hint="整的啥吧"
        />

    <Button
        android:id="@+id/fm_title_button_id"
        android:text="发送了啊"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

fragment 给 fragment 传值
第一种：
动态创建的fragment通过findFragmentByTag得到另一个的Fragment的对象，这样就可以调用另一个的方法了。
静态创建的fragment通过findFragmentById得到另一个的Fragment的对象，这样就可以调用另一个的方法了。

package com.example.day005.fragment;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import com.example.day005.R;

/**
 * A simple {@link Fragment} subclass.
 */
public class LeftFragment extends Fragment {

    private EditText editText;
    private Button send_button;

    public LeftFragment() {
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View inflate = inflater.inflate(R.layout.fragment_left, container, false);
        editText = inflate.findViewById(R.id.left_textView_id);
        send_button = inflate.findViewById(R.id.left_button_id);

        send_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String string = editText.getText().toString();
                
                **了解一种即可,不重点**
                //1 fragment传值方式1
                // 通过id找的指定fragment,调用他的方法,给他的组件赋值.
                FragmentManager fragmentManager = getFragmentManager(); //注意,这个manager是v4包下的.
                RightFragment rightFragment=(RightFragment) fragmentManager.findFragmentById(R.id.right_fragment_id);
                rightFragment.setTextView(string);

                //2 通过id找的指定fragment,得到他所有的view.在通过findViewById 找到组件.赋值
                TextView textView = getFragmentManager().findFragmentById(R.id.right_fragment_id).getView().findViewById(R.id.right_textview_id);
                textView.setText(string);

                //3
                //因为两个fragment在一个activity里面,所有可以通过拿到activity里面所有的指定组件.
                TextView textView = (TextView) getActivity().findViewById(R.id.right_textview_id);
                textView.setText(string);

            }
        });
        return inflate;
    }
}

第二种(重点)

通过接口回调的方式。
与上面的接口回调用法相同

第三种：
通过setArguments，getArguments的方式。

fragment 多层嵌套

与正常使用区别不大

 FragmentManager childFragmentManager = getChildFragmentManager();
 FragmentTransaction fragmentTransaction = childFragmentManager.beginTransaction();
 fragmentTransaction.add(R.id.left_fragment_id,new RightFragment());
 fragmentTransaction.commit();

案例(微信底部按钮与fragment实现界面切换)
activity中的代码

package com.example.day004.activities;

import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.FrameLayout;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;

import com.example.day004.R;
import com.example.day004.fragment.FristFragment;
import com.example.day004.fragment.SecondFragment;

/**
 * 底部导航
 */
public class SelectActivity extends AppCompatActivity {
    private FrameLayout frameLayoutId;
    private RadioGroup radioGroupId;
    private RadioButton personId;
    private RadioButton messageId;
    private static final String TAG = "SelectActivity";
    private FragmentManager manager;
    private FragmentTransaction fragmentTransaction;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_select);

        frameLayoutId = findViewById(R.id.frame_layout_id);
        radioGroupId = findViewById(R.id.radio_group_id);

        radioGroupId.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                switch (checkedId) {
                    case R.id.person_id:
                        manager = getSupportFragmentManager();
                        fragmentTransaction = manager.beginTransaction();
//                        fragmentTransaction.replace(R.id.frame_layout_id,new FristFragment());
                        fragmentTransaction.add(R.id.frame_layout_id,new FristFragment());
                        fragmentTransaction.addToBackStack("11");
                        Log.i(TAG, "onCheckedChanged: "+SelectActivity.class.getName());
                        fragmentTransaction.commit();
                        break;
                    case R.id.message_id:
                        manager = getSupportFragmentManager();
                        manager.popBackStack();
                        SelectActivity.this.fragmentTransaction = manager.beginTransaction();
                        SelectActivity.this.fragmentTransaction.replace(R.id.frame_layout_id,new SecondFragment());
//                        fragmentTransaction.addToBackStack(null);
                        SelectActivity.this.fragmentTransaction.commit();
                        break;
                    default:
                        break;
                }
            }
        });
    }
}

activity的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=".activities.SelectActivity">

    <FrameLayout
        android:id="@+id/frame_layout_id"
        android:layout_weight="9"
        android:layout_width="match_parent"
        android:layout_height="0dp">
    </FrameLayout>

    <RadioGroup
        android:id="@+id/radio_group_id"
        android:layout_weight="1"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="0dp">

        <RadioButton
            android:layout_weight="1"
            android:id="@+id/person_id"
            android:button="@null"
            android:text="联系人"
            android:gravity="center"
            android:checked="true"
            android:drawableTop="@drawable/select_pserson"
            android:textColor="@drawable/select_text"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            />

        <RadioButton
            android:layout_weight="1"
            android:id="@+id/message_id"
            android:button="@null"
            android:gravity="center"
            android:drawableTop="@drawable/select_message"
            android:textColor="@drawable/select_text"
            android:text="信息"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            />
    </RadioGroup>

</LinearLayout>

说明
android:drawableTop="@drawable/select_message"
android:textColor="@drawable/select_text"
这两个属性,参照下面链接创建
https://blog.csdn.net/qq_34178710/article/details/91411003
java代码中的fragment,右键创建即可.

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黑客李黑蛋 发布了5 篇原创文章 · 获赞 0 · 访问量 117 私信 关注

标签：进阶,Fragment,高级,public,fragment,import,android,fragmentTransaction,id
来源： https://blog.csdn.net/Lee_black_eggs/article/details/104558127