动态创建Fragment

package com.bawei.yuekao2.activity;

import android.content.ContentValues;
import android.os.AsyncTask;
import android.os.Handler;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ListView;
import android.widget.RadioGroup;
import android.widget.Toast;

import com.bawei.yuekao2.R;
import com.bawei.yuekao2.adapter.Myadapter;
import com.bawei.yuekao2.base.BaseActivity;
import com.bawei.yuekao2.bean.JsonBean;
import com.bawei.yuekao2.frag.Frag_01;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshListView;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;

public class MainActivity extends BaseActivity {
private Fragment perfragment;
private int page=1;

private RadioGroup radioGroup;
private DrawerLayout dl;
private PullToRefreshListView pul;

@Override
protected int layoutResID() {
    return R.layout.activity_main;
}

@Override
protected void initView() {
    radioGroup = findViewById(R.id.radiogroup);
    dl = findViewById(R.id.dl);
    pul = findViewById(R.id.pul);
}

@Override
protected void initData() {
    //侧拉监听
    dl.addDrawerListener(new DrawerLayout.DrawerListener() {
        @Override
        public void onDrawerSlide(@NonNull View view, float v) {

        }

        @Override
        public void onDrawerOpened(@NonNull View view) {
            Toast.makeText(MainActivity.this, "侧拉打开啦", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onDrawerClosed(@NonNull View view) {
            Toast.makeText(MainActivity.this, "侧拉关闭啦", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onDrawerStateChanged(int i) {

        }
    });


    //创建一个方法
    addFragment(Frag_01.newInstance(0));
    radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            int i = radioGroup.indexOfChild(radioGroup.findViewById(checkedId));
            addFragment(Frag_01.newInstance(i));
        }
    });

ragmentManager = getSupportFragmentManager();
    FragmentTransaction transaction = fragmentManager.beginTransaction();
    if (frag_01.isAdded()){
        transaction.show(frag_01).commit();
    }
    else {
        transaction.add(R.id.frag,frag_01).commit();
    }
    if (perfragment!=null){
        transaction.hide(perfragment);
    }
    perfragment=frag_01;
}

}