Anroid studio遇到的问题8---wrong 2nd argument type found 'android.app.Fragment.' required 'Android.suppo

8. wrong 2nd argument type found 'android.app.Fragment.' required 'Android.support.v4.app.Fragment'

rt，使用fragment的时候报以上错误。

<code class="hljs ocaml has-numbering">wrong <span class="hljs-number">2</span>nd argument <span class="hljs-class"><span class="hljs-keyword">type</span> <span class="hljs-title">found</span></span><span class="hljs-string">'android.support.v4.app.Fragment.'</span> required <span class="hljs-string">'Android.app.Fragment'</span></code><ul style="" class="pre-numbering"><li>1</li><li>2</li></ul>

解决了半天！发现错误其实很简单，首要的是解读错误信息：第二个参数类型为android.app.Fragment，要求Android.app.support.v4.Fragment类型（其实就是参数类型错误）

---

Fragment是界面的一部分，经常被用于滑动界面，可以将多个fragment组合用于一个activity中，它具有生命周期和事件。

Fragment的包为 android.app.Fragment， 但是由于其对3.0下版本不兼容，所以要 引入 android.support.v4.app.Fragment 两个包对Fragment相同方法的定义有所不同，因此在import时，经常容易混淆导致程序报错！！！（以下是我的部分代码）

<code class="hljs avrasm has-numbering">import android<span class="hljs-preprocessor">.support</span><span class="hljs-preprocessor">.v</span>4<span class="hljs-preprocessor">.app</span><span class="hljs-preprocessor">.FragmentManager</span><span class="hljs-comment">;</span>import android<span class="hljs-preprocessor">.support</span><span class="hljs-preprocessor">.v</span>4<span class="hljs-preprocessor">.app</span><span class="hljs-preprocessor">.FragmentTransaction</span><span class="hljs-comment">;</span>import <span class="hljs-keyword">com</span><span class="hljs-preprocessor">.gym</span><span class="hljs-preprocessor">.zgbj</span><span class="hljs-preprocessor">.Fragment</span><span class="hljs-preprocessor">.LeftMenuFragment</span><span class="hljs-comment">;</span>import <span class="hljs-keyword">com</span><span class="hljs-preprocessor">.gym</span><span class="hljs-preprocessor">.zgbj</span><span class="hljs-preprocessor">.Fragment</span><span class="hljs-preprocessor">.ContentFragment</span><span class="hljs-comment">;</span> private void initFragment() {        FragmentManager fm = getSupportFragmentManager()<span class="hljs-comment">;</span>        FragmentTransaction transaction = fm<span class="hljs-preprocessor">.beginTransaction</span>()<span class="hljs-comment">;// 开始事务</span>        transaction<span class="hljs-preprocessor">.replace</span>(R<span class="hljs-preprocessor">.id</span><span class="hljs-preprocessor">.fl</span>_left_menu, new LeftMenuFragment(),                TAG_LEFT_MENU)<span class="hljs-comment">;// 用fragment替换帧布局;参1:帧布局容器的id;参2:是要替换的fragment;参3:标记</span>        transaction<span class="hljs-preprocessor">.replace</span>(R<span class="hljs-preprocessor">.id</span><span class="hljs-preprocessor">.fl</span>_main, new ContentFragment(), TAG_CONTENT)<span class="hljs-comment">;</span>        transaction<span class="hljs-preprocessor">.commit</span>()<span class="hljs-comment">;// 提交事务</span>        // Fragment fragment =        // fm<span class="hljs-preprocessor">.findFragmentByTag</span>(TAG_LEFT_MENU)<span class="hljs-comment">;//根据标记找到对应的fragment</span>    }</code><ul style="" class="pre-numbering"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li></ul>

<code class="hljs avrasm has-numbering"> transaction<span class="hljs-preprocessor">.replace</span>(R<span class="hljs-preprocessor">.id</span><span class="hljs-preprocessor">.fl</span>_left_menu, new LeftMenuFragment(), TAG_LEFT_MENU)<span class="hljs-comment">;</span></code><ul style="" class="pre-numbering"><li>1</li><li>2</li></ul>

在transaction.replace这一条语句报了错！其实看以上代码并发现不了错误，我导入的是android.support.v4.app包，而且在获取FragmentManager 使用的也是getSupportFragmentManager函数。一步步推理，
最终发现是LeftMenuFragment继承的Fragment，导入的是Android.app.Fragment包!
所以错误还是导错包！！！！！！！（泪奔）

---

---

总结

1.如果你导入的是Android.app.Fragment’包（即本地的jar包）
import android.app.Fragment;
那么在获得FragmentManager时，使用的应该是
FragmentManager fm = getFragmentManager();，对应的fragment也要导入对应的包！

---

2.如果你导入的是android.support.v4.app.Fragment.包（即v4包）
import android.support.v4.app.Fragment;
那么在获得FragmentManager时，使用的应该是
FragmentManager fm = getSupportFragmentManager();
对应的fragment也要导入对应的包！

---

一定要注意你所继承的fragment，导入的是哪个包！

这个讲解了fragment，学习学习
http://blog.csdn.net/qq_16444837/article/details/48183877