学习笔记之ViewPager

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今天看ViewPager的官方文档，官方做了一个ActionBar tabs和Fragment组合的例子 

在 class TabsAdapter extends FragmentPagerAdapter中 

有一句代码，没怎么见过

@Override
public Fragment getItem(int position) {
TabInfo info = mTabs.get(position);
return Fragment.instantiate(mContext, info.clss.getName(), info.args);
}

就是这个通过ClassName获取Fragment的方法，这是源代码：

/**
* Create a new instance of a Fragment with the given class name.  This is
* the same as calling its empty constructor.
*
* @param context The calling context being used to instantiate the fragment.
* This is currently just used to get its ClassLoader.
* @param fname The class name of the fragment to instantiate.
* @param args Bundle of arguments to supply to the fragment, which it
* can retrieve with {@link #getArguments()}.  May be null.
* @return Returns a new fragment instance.
* @throws InstantiationException If there is a failure in instantiating
* the given fragment class.  This is a runtime exception; it is not
* normally expected to happen.
*/
public static Fragment instantiate(Context context, String fname, @Nullable Bundle args) {
try {
Class<?> clazz = sClassMap.get(fname);
if (clazz == null) {
// Class not found in the cache, see if it's real, and try to add it
clazz = context.getClassLoader().loadClass(fname);
if (!Fragment.class.isAssignableFrom(clazz)) {
throw new InstantiationException("Trying to instantiate a class " + fname
+ " that is not a Fragment", new ClassCastException());
}
sClassMap.put(fname, clazz);
}
Fragment f = (Fragment)clazz.newInstance();
if (args != null) {
args.setClassLoader(f.getClass().getClassLoader());
f.mArguments = args;
}
return f;
} catch (ClassNotFoundException e) {
throw new InstantiationException("Unable to instantiate fragment " + fname
+ ": make sure class name exists, is public, and has an"
+ " empty constructor that is public", e);
} catch (java.lang.InstantiationException e) {
throw new InstantiationException("Unable to instantiate fragment " + fname
+ ": make sure class name exists, is public, and has an"
+ " empty constructor that is public", e);
} catch (IllegalAccessException e) {
throw new InstantiationException("Unable to instantiate fragment " + fname
+ ": make sure class name exists, is public, and has an"
+ " empty constructor that is public", e);
}
}

不多说啦，我只是菜