Android开发新闻购物类列表并查看详细信息的实现（总结）

比如，一个新闻类APP（或者购物类），你点击新闻列表中的某一项后，弹出详细信息界面。这个效果，有两种实现的方法：

1、两个Activity来实现，数据通过Bundle封装然后Intent来传输。（这个不太好，每次关闭返回，列表Activity都会刷新置顶显示，当然可以通过其他手段解决这个问题，不过还是感觉比较麻烦！）

2、两个Fragment（Activity片段）来实现。（通过Fragment栈的addtobackStack和popbackstack来解决上面的问题，很方便！）

（完整Demo地址：https://download.csdn.net/download/lpcrazyboy/10516232）

效果图如下：

主要思路：

1、创建一个NewsListFragment.java继承自Fragment，这个Fragment用于显示ListView，即新闻列表。并且，在该Fragment中给ListView添加OnItemClickListener监听事件，用于触发item点击，然后创建一个NewsContentFragment对象，replace一下。

2、创建一个NewsContentFragment.java继承自Fragment，这个Fragment用于显示新闻的详细内容。获取到ListView中触发点击之后传过来的Bundle对象，接着再获取相应的内容并显示。

3、创建一个MyListAdapter.java继承自BaseAdapter，这个数据适配器用于向ListView中填充内容。（这个很简单，就是自定义个数据适配器）

4、在MainActivity.java中默认显示NewsListFragment对象。

PS：如果出现下面的问题，在类的前面加上@SuppressLint("ValidFragment")即可

use a default constructor plus Fragment#setArguments(Bundle)


主要代码如下：

NewsListFragment.java

package com.deepreality.fragmentcasefourdemo;

import android.annotation.SuppressLint;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListView;

import java.util.List;

@SuppressLint("ValidFragment")
public class NewsListFragment extends Fragment implements AdapterView.OnItemClickListener {

    private ListView lvNewsList;
    private FragmentManager fragmentManager;
    private List<Data> dataList;

    public NewsListFragment() {
        super();
    }

    public NewsListFragment(FragmentManager fragmentManager, List<Data> dataList) {
        super();
        this.fragmentManager = fragmentManager;
        this.dataList = dataList;
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fg_newslist, container, false);
        lvNewsList = view.findViewById(R.id.newslist_lvNewsList);
        MyListAdapter myListAdapter = new MyListAdapter(getActivity(), dataList);
        lvNewsList.setAdapter(myListAdapter);
        lvNewsList.setOnItemClickListener(this);
        return view;
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        Bundle bundle = new Bundle();
        bundle.putString("content", dataList.get(position).getNew_content());
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        NewsContentFragment newsContentFragment = new NewsContentFragment(bundle);

    
        fragmentTransaction.replace(R.id.main_fLayoutFragment, newsContentFragment);
        //调用addToBackStack将Fragment添加到栈中
        fragmentTransaction.addToBackStack(null);
        fragmentTransaction.commit();
    }
}

NewsContentFragment.java

package com.deepreality.fragmentcasefourdemo;

import android.annotation.SuppressLint;
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;

@SuppressLint("ValidFragment")
public class NewsContentFragment extends Fragment {
    private TextView tvNewsContent;
    private String content;

    public NewsContentFragment() {
        super();
    }

    public NewsContentFragment(Bundle bundle) {
        this.content = bundle.getString("content");
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fg_content, container, false);
        tvNewsContent = view.findViewById(R.id.content_tvContent);
        tvNewsContent.setText(content);
        return view;
    }
}

MainActivity.java

package com.deepreality.fragmentcasefourdemo;

import android.app.FragmentManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.FrameLayout;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private FrameLayout fLayoutFragment;
    private List<Data> dataList;
    private FragmentManager fragmentManager;
    private long exitTime = 0;

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

        fragmentManager = getFragmentManager();
        fLayoutFragment = findViewById(R.id.main_fLayoutFragment);
        dataList = new ArrayList<Data>();
        for (int i = 1; i <= 20; i++) {
            Data data = new Data("新闻标题" + i, i + "~新闻内容~~~~~~~~");
            dataList.add(data);
        }

        NewsListFragment newsListFragment = new NewsListFragment(fragmentManager, dataList);
        fragmentManager.beginTransaction().replace(R.id.main_fLayoutFragment, newsListFragment).commit();
    }

    //点击回退键的处理：判断Fragment栈中是否有Fragment
    //没，双击退出程序，否则像是Toast提示
    //有，popbackstack弹出栈
    @Override
    public void onBackPressed() {
        if (fragmentManager.getBackStackEntryCount() == 0) {
            if ((System.currentTimeMillis() - exitTime) > 2000) {
                Toast.makeText(getApplicationContext(), "再按一次退出程序",
                        Toast.LENGTH_SHORT).show();
                exitTime = System.currentTimeMillis();
            } else {
                super.onBackPressed();
            }
        } else {
            fragmentManager.popBackStack();
        }
    }
}