Question

我的结构是什么：

我有一个名为MainActivity.java
在MainActivity.java内ParentFragment.java
现在ParentFragment.java内有ChildFragment.Java
现在ChildFragment.Java里面有一个适配器 ChildAdapter.java
在ChildAdapter.java内，这是一个名为MyMethod()

现在如何访问MyMethod() 中的MainActivity.java

Answer 1

这是解决方案

1.通过标签ParentFragment在MainActivity中查找ParentFragemnt

2.来自ChildFragment实例使用getChildSupportManager()找到ChildAdapter及其TAG

3.现在在ChildFragment中创建ChildFragment变量全局变量并公开

4.从ChildAdapter实例访问MyMethod()

5.您可以从ChildAdapter变量

访问

public class Book{
private String title;
private String isbn;
//.... other properties of the book.

//constructors
//getters and setters
public String getTitle(){
     return title;
}

public void setTitle(String title){
     this.title= title;
}
//do the same for isbn
//overriding toString, equals and hash...

}

public class library{
   private List<Book> books = new ArrayList<>();
   /* help methods like getCount which get size of books ArrayList, clear method 
    * which clears the books ArrayList, and other help methods you need.
    */
}

Answer 2

我通常在Activity中使用此方法，该方法必须替换Fragments：

 /**
 * This method is used to load the fragment once an item gets selected
 *
 * @param fragment This is the chosen fragment you want to select
 */
public void loadFragmentActivityFrameLayout(final Fragment fragment) {

    // create a transaction for transition here
    final FragmentTransaction transaction = getSupportFragmentManager()
            .beginTransaction();

    // put the fragment in place
    transaction.replace(
            R.id.frameLayoutId,
            fragment,
            fragment.getClass().getSimpleName());

    // this is the part that will cause a fragment to be added to back stack,
    // this way we can return to it at any time using this tag
        if(fragment instanceof Fragment1){
            transaction.addToBackStack(Fragmen1.class.getSimpleName());
        }else if(fragment instanceof Fragment2){
            transaction.addToBackStack(Fragment2.class.getSimpleName());
        }else if(fragment instance of Fragment3){
            transaction.addToBackStack(Fragment3.class.getSimpleName());
        }else if(fragment instanceof Fragment4){
            transaction.addToBackStack(Fragment4.class.getSimpleName());
        }

    transaction.commit();
}

然后您可以在该Activity中检索每个Fragment的实例，如下所示：

Fragment1 frag1 =
            (Fragment1)getSupportFragmentManager()
                    .findFragmentByTag(Fragment1.class.getSimpleName());

Fragment2 frag2  =
            (Fragment2)getSupportFragmentManager()
                    .findFragmentByTag(Fragment2.class.getSimpleName());

Fragment3 frag3 =
            (Fragment3)getSupportFragmentManager()
                    .findFragmentByTag(Fragment3.class.getSimpleName());

Fragment4 frag4 =
            (Fragment4)getSupportFragmentManager()
                    .findFragmentByTag(Fragment4.class.getSimpleName());

然后，既然你有一个适配器，让它在片段中公开，让我们说“frag1”，不要忘记让“MyMethod（）”也公开进入适配器：< / p>

public CustomAdapter adapter;

最后，您可以从Activity：

中检索任何适配器方法

frag1.adapter.MyMethod();

希望我一直很清楚。

如何从android中的活动中调用子片段方法的适配器的功能

2 个答案: