Android Fragment和Activity数据或对象的传递总结

小灰灰 2022-06-17 05:56 448阅读 0赞

# Android Fragment和Activity数据或对象的传递总结 #

### 本文将展示Activity和Fragment之间、Fragment和Fragment的数据传递和对象改变，并作简要说明。 ###

# 一．基础知识 #

## （一）Activity获取Fragment的对象 ##

### 1.可以通过findViewById或findViewByTag找到，一般用于静态创建的Fragment ###

//获取碎片A的对象 
    fragmentA= (FragmentA) getActivity().getSupportFragmentManager().findFragmentById(R.id.main_frag1);

### 2.可以通过Fragment的集合对象获取到，一般用于动态创建的Fragment ###

比如获取碎片集合中的第一个碎片对象： 
     Fragment1 fragment1 = (Fragment1) getSupportFragmentManager().getFragments().get(0);

## （二）Fragment中获取到Acitvity中的对象 ##

这个就简单了，直接个体Activity然后强转成对应的Activity就可以了

MyActivity myActivity = (MyActivity) (getActivity());

# 二．示例 #

## 实现：Activity可以读取并改变Fragment1和Fragment2对象的数据。同时，Fragment1可以读取和改变Activity和Fragment2的数据。Fragment2也是读取和改变Fragment1和Activity中的数据。 ##

### 效果： ###

![s][]

### 动态效果图： ###

![s2][]  
2  
![s3][]  
这里贴一下MyActivity和Fragment1的代码

### MyActivity： ###

package com.example.viewPager2;
    
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentActivity;
    import android.support.v4.app.FragmentManager;
    import android.support.v4.app.FragmentStatePagerAdapter;
    import android.support.v4.view.ViewPager;
    import android.view.View;
    import android.widget.TextView;
    import android.widget.Toast;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class MyActivity extends FragmentActivity {
        
    
        List<Fragment> list = new ArrayList<Fragment>();
        ViewPager viewPager;
    
        String myActivityString;
        User myActivityUser;
        TextView tv_main_show;
    
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            myActivityString = new String("这是MyActivity的字符串");
            myActivityUser = new User("myActivityUser", 18);
            Fragment1 fragmemt1 = new Fragment1();
            Fragment2 fragmemt2 = new Fragment2();
            list.add(fragmemt1);
            list.add(fragmemt2);
            viewPager = (ViewPager) findViewById(R.id.home_vp);
            tv_main_show = (TextView) findViewById(R.id.tv_main_show);
            //创建适配器,设置的碎片管理器使用的是getChildFragmentManager()
            Myadapter adapter = new Myadapter(getSupportFragmentManager());
    
            //给ViewPager设置适配器
            viewPager.setAdapter(adapter);
        }
    
        //创建ViewPager适配器的类
        class Myadapter extends FragmentStatePagerAdapter {
    
            public Myadapter(FragmentManager fm) {
                super(fm);
            }
    
            @Override
            public Fragment getItem(int position) {
                return list.get(position);
            }
    
            @Override
            public int getCount() {
                return list.size();
            }
        }
    
        /**
         * 获取Fragment1中的数据
         *
         * @param view
         */
        public void getFragment1Data(View view) {
    
            String msg = ((Fragment1) getSupportFragmentManager().getFragments().get(0)).fragment1String;
            User msg2 = ((Fragment1) getSupportFragmentManager().getFragments().get(0)).fragment1User;
            Toast.makeText(this, msg + msg2, Toast.LENGTH_SHORT).show();
        }
    
        /**
         * 获取Fragment2中的数据
         *
         * @param view
         */
        public void getFragment2Data(View view) {
            String msg = ((Fragment2) getSupportFragmentManager().getFragments().get(1)).fragment2String;
            User msg2 = ((Fragment2) getSupportFragmentManager().getFragments().get(1)).fragment2User;
            Toast.makeText(this, msg + msg2, Toast.LENGTH_SHORT).show();
        }
    
        /**
         * 改变Fragment1中显示的内容
         */
        public void changeFragment1Data(View view) {
            Fragment1 fragment1 = (Fragment1) getSupportFragmentManager().getFragments().get(0);
            fragment1.tv_fragment1_show.append("\nMyActivity在这里改变了数据");
        }
    
        /**
         * 改变Fragment2中显示的内容
         */
        public void changeFragment2Data(View view) {
            Fragment2 fragment2 = (Fragment2) getSupportFragmentManager().getFragments().get(1);
            fragment2.tv_fragment2_show.append("\nMyActivity在这里改变了数据");
    
        }
    
    }

### Fragment1： ###

package com.example.viewPager2;
    
    import android.os.Bundle;
    import android.support.annotation.Nullable;
    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.TextView;
    import android.widget.Toast;
    
    /**
     * 碎片页面1
     */
    public class Fragment1 extends Fragment implements View.OnClickListener {
        
    
    
        String fragment1String;
        User fragment1User;
        TextView tv_fragment1_show;
    
        @Override
        public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
            fragment1String = new String("这是Fragment1页面的数据");
            fragment1User = new User("fragment1User", 88);
            View view = inflater.inflate(R.layout.fragment1, null);
            Button btn_getMyActivityData = (Button) view.findViewById(R.id.btn_getMyActivityData);
            Button btn_getFragment2Data = (Button) view.findViewById(R.id.btn_getFragment2Data);
            Button btn_changeMyActivityData = (Button) view.findViewById(R.id.btn_changeMyActivityData);
            Button btn_changeFragment2Data = (Button) view.findViewById(R.id.btn_changeFragment2Data);
            tv_fragment1_show = (TextView) view.findViewById(R.id.tv_fragment1_show);
    
            btn_getMyActivityData.setOnClickListener(this);
            btn_getFragment2Data.setOnClickListener(this);
            btn_changeMyActivityData.setOnClickListener(this);
            btn_changeFragment2Data.setOnClickListener(this);
            return view;
        }
    
    
        @Override
        public void onClick(View v) {
            String msg = "";
            User user = null;
    
            /**
             * 获取MyActivity中的数据
             */
            if (v.getId() == R.id.btn_getMyActivityData) {
                msg = ((MyActivity) (getActivity())).myActivityString;
                user = ((MyActivity) (getActivity())).myActivityUser;
                Toast.makeText(getActivity(), msg + user, Toast.LENGTH_SHORT).show();
            }
    
            /**
             * 获取Fragment2中的数据
             */
            if (v.getId() == R.id.btn_getFragment2Data) {
                msg = ((Fragment2) getFragmentManager().getFragments().get(1)).fragment2String;
                user = ((Fragment2) getFragmentManager().getFragments().get(1)).fragment2User;
                Toast.makeText(getActivity(), msg + user, Toast.LENGTH_SHORT).show();
            }
    
            /**
             * 改变MyActivity中的数据
             */
            if (v.getId() == R.id.btn_changeMyActivityData) {
                MyActivity myActivity = (MyActivity) (getActivity());
                myActivity.tv_main_show.append("\nFragment1改变了这里的数据");
            }
    
    
            /**
             * 改变Fragment2中的数据
             */
            if (v.getId() == R.id.btn_changeFragment2Data) {
                Fragment2 fragment2 = (Fragment2) getFragmentManager().getFragments().get(1);
                fragment2.tv_fragment2_show.append("\nFragment1改变了这里的数据");
            }
        }
    }

### 有时候使用Fragmentd相关类报错，有可能是V4包的源码有问题（版本原因）,我的项目里有正确的v4包。 ###

这个项目的源码地址：  
[http://download.csdn.net/detail/wenzhi20102321/9818301][http_download.csdn.net_detail_wenzhi20102321_9818301]

关于Fragment和ViewPage的详细使用和相关知识的总结，很早以前写过：  
还是比较详细的：

### Fragment： ###

[http://blog.csdn.net/wenzhi20102321/article/details/53572610][http_blog.csdn.net_wenzhi20102321_article_details_53572610]

### ViewPager和Fragment： ###

[http://blog.csdn.net/wenzhi20102321/article/details/53584344][http_blog.csdn.net_wenzhi20102321_article_details_53584344]

共勉：哪个人成功会随随便便！

[s]: /images/20220617/66c9be79ea9f408d9faab12569a2fe79.png
[s2]: /images/20220617/1661a3654ad840b8b44059df1ead9a1f.png
[s3]: /images/20220617/fc308d8f53f64d76b403ff2cdbdb5339.png
[http_download.csdn.net_detail_wenzhi20102321_9818301]: http://download.csdn.net/detail/wenzhi20102321/9818301
[http_blog.csdn.net_wenzhi20102321_article_details_53572610]: http://blog.csdn.net/wenzhi20102321/article/details/53572610
[http_blog.csdn.net_wenzhi20102321_article_details_53584344]: http://blog.csdn.net/wenzhi20102321/article/details/53584344