用了例程的源码 为什么tab的内容没有显示？？

Question

package com.example.ghost.text1; 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.FragmentTransaction; import android.view.View; import android.view.Window; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.TextView; /**  * Created by GHOST on 2017/1/28.  * Fragment  */ public class tabActivity extends FragmentActivity implements View.OnClickListener {     // 四个tab布局     private LinearLayout takeOutLayout, expressLayout, personLayout, nearbyLayout;     // 底部标签切换的Fragment     private Fragment takeOutFragment, expressFragment, personFragment, nearbyFragment;     // 底部标签图片     private ImageView takeOutImg, expressImg, nearbyImg, personImg;     private TextView takeoutTv, expressTv, nearbyTv, presonTv;     @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         requestWindowFeature(Window.FEATURE_NO_TITLE);         setContentView(R.layout.main_menu);         initView();         initEvent();         setSelect(0);     }     private void initEvent() {         takeOutLayout.setOnClickListener(this);         expressLayout.setOnClickListener(this);         nearbyLayout.setOnClickListener(this);         personLayout.setOnClickListener(this);     }     private void initView() {         takeOutLayout = (LinearLayout) findViewById(R.id.id_tab_takeout);         expressLayout = (LinearLayout) findViewById(R.id.id_tab_express);         nearbyLayout = (LinearLayout) findViewById(R.id.id_tab_nearby);         personLayout = (LinearLayout) findViewById(R.id.id_tab_person);         takeOutImg = (ImageView) findViewById(R.id.id_tab_takeout_img);         expressImg = (ImageView) findViewById(R.id.id_tab_express_img);         nearbyImg = (ImageView) findViewById(R.id.id_tab_nearby_img);         personImg = (ImageView) findViewById(R.id.id_tab_person_img);     }     private void setSelect(int i) {         FragmentManager fm = getSupportFragmentManager();         FragmentTransaction transaction = fm.beginTransaction();         hideFragment(transaction);         // 把图片设置为亮的         // 设置内容区域         switch (i) {             case 0:                 if (takeOutFragment == null) {                     takeOutFragment = new tab1_fragment();                     transaction.add(R.id.id_content, takeOutFragment);                 } else {                     transaction.show(takeOutFragment);                 }                 takeOutImg.setImageResource(R.drawable.tab_1);                 break;             case 1:                 if (expressFragment == null) {                     expressFragment = new tab2_fragment();                     transaction.add(R.id.id_content, expressFragment);                 } else {                     transaction.show(expressFragment);                 }                 expressImg.setImageResource(R.drawable.tab_2);                 break;             case 2:                 if (nearbyFragment == null) {                     nearbyFragment = new tab3_fragment();                     transaction.add(R.id.id_content, nearbyFragment);                 } else {                     transaction.show(nearbyFragment);                 }                 nearbyImg.setImageResource(R.drawable.tab_3);                 break;             case 3:                 if (personFragment == null) {                     personFragment = new tab4_fragment();                     transaction.add(R.id.id_content, personFragment);                 } else {                     transaction.show(personFragment);                 }                 personImg.setImageResource(R.drawable.tab_4);                 break;             default:                 break;         }         transaction.commit();     }     private void hideFragment(FragmentTransaction transaction) {         if (takeOutFragment != null) {             transaction.hide(takeOutFragment);         }         if (expressFragment != null) {             transaction.hide(expressFragment);         }         if (nearbyFragment != null) {             transaction.hide(nearbyFragment);         }         if (personFragment != null) {             transaction.hide(personFragment);         }     }     @Override     public void onClick(View v) {         resetImgs();         switch (v.getId()) {             case R.id.id_tab_takeout:                 setSelect(0);                 break;             case R.id.id_tab_express:                 setSelect(1);                 break;             case R.id.id_tab_nearby:                 setSelect(2);                 break;             case R.id.id_tab_person:                 setSelect(3);                 break;             default:                 break;         }     }     private void resetImgs() {         takeOutImg.setImageResource(R.drawable.tab_1_1);         expressImg.setImageResource(R.drawable.tab_2_2);         nearbyImg.setImageResource(R.drawable.tab_3_3);         personImg.setImageResource(R.drawable.tab_4_4);     } }<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="vertical" >     <TextView         android:layout_width="fill_parent"         android:layout_height="fill_parent"         android:gravity="center"         android:text="This is a Tab"         android:textSize="30sp"         android:textStyle="bold" /> </LinearLayout>package com.example.ghost.text1; import android.os.Bundle; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; public class tab1_fragment extends Fragment {     public View onCreate(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {         return   inflater.inflate(R.layout.tab01, container, false);     } }

Answer 1

是不是默认显示哪个界面的问题

Answer 2

代码贴全一点好吗，这样怎么看，提问的时候设置一下代码语言，不要直接复制粘贴