fragment-实例创建跟使用

今天接触到了fragment，在网上看到了它的使用方法。现在把它的创建跟使用记录下，方便以后查询。

1.创建一个自己的fragment，继承自fragment

package com.android.calculator2;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ListView;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;

public class HistoryFragment extends Fragment {
private View mView;
private ListView mListView;
private Button mClearHistoryBtn;
private Button mBackCalculatorBtn;
private HistoryAdapter mHistoryAdapter;
private Animation myAnimationIn;
private Animation myAnimationOut;

public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
mView = inflater.inflate(R.layout.history_display, container, false);
myAnimationIn = AnimationUtils.loadAnimation(getActivity(), R.anim.history_fragment_in_anim);
myAnimationOut = AnimationUtils.loadAnimation(getActivity(),R.anim.history_fragment_out_anim);
myAnimationIn.setFillAfter(true);
myAnimationOut.setFillAfter(true);
if (mView != null) {
mView.startAnimation(myAnimationIn);
mClearHistoryBtn = (Button) mView.findViewById(R.id.history_clear);
mBackCalculatorBtn = (Button) mView.findViewById(R.id.history_back);
mListView = (ListView) mView.findViewById(R.id.history_list);
if (getActivity() instanceof HistoryClickListener) {
mHistoryAdapter = ((HistoryClickListener) getActivity()).getHistoryAdapter();
}
mListView.setAdapter(mHistoryAdapter);
mBackCalculatorBtn.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View arg0) {
if (getActivity() instanceof HistoryClickListener) {
((HistoryClickListener) getActivity()).historyClickHide();
}

}
});
mClearHistoryBtn.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
if (getActivity() instanceof HistoryClickListener) {
((HistoryClickListener) getActivity()).historyClickClear();
}

}
});

return mView;
} else {
return super.onCreateView(inflater, container, savedInstanceState);
}

}

public interface HistoryClickListener {
void historyClickHide();
void historyClickClear();
HistoryAdapter getHistoryAdapter();
}
@Override
public void onDestroyView() {
if (mView != null) {
mView.startAnimation(myAnimationOut);
}
super.onDestroyView();
}
}

然后在代码中使用

FragmentManager mHistoryFm = getFragmentManager();
FragmentTransaction mHistoryTx = mHistoryFm.beginTransaction();
mHistoryTx.replace(R.id.frame_layout, mHistoryFragment, "history");
mHistoryTx.addToBackStack(null);
mHistoryTx.commit();

它的使用也很简单。只需要创建，然后在activity中加载到一个布局里面就行了。

有以下几点需要注意

1.你必须在activity的xml中分配一个布局容器给你的fragment，就是方法里面的

mHistoryTx.replace(R.id.frame_layout, mHistoryFragment, "history");

R.id.frame_layout

2.如果你想移除一个fragment，你必须拥有这个fragment的实例，也就是

mHistoryTx.replace(R.id.frame_layout, mHistoryFragment, "history");
mHistoryTx.remove( mHistoryFragment);

上面的两个mHistoryFragment是同一个实例

3.尽量让fragment中事件的处理，交给activity来处理。常用的方法就是

在fragment想要实现的操作，定义为一个接口，然后在activity中实现这个接口

定义接口

public interface HistoryClickListener {
void historyClickHide();
void historyClickClear();
HistoryAdapter getHistoryAdapter();
}

实现接口

public class Calculator extends Activity implements Logic.Listener, HistoryClickListener{

@Override
public void historyClickHide() {
android.util.Log.e("zhangshuli", "mmmm");
FragmentManager mHistoryFm = getFragmentManager();
FragmentTransaction mHistoryTx = mHistoryFm.beginTransaction();
mHistoryTx.remove(mHistoryFragment);
mHistoryTx.commit();
}

@Override
public void historyClickClear() {
android.util.Log.e("zhangshuli", "nnnn");
mHistory.clear();
mLogic.onClear();
}

@Override
public HistoryAdapter getHistoryAdapter() {
return mAdapter;
}

}

在fragment中回调activity中的方法

if (getActivity() instanceof HistoryClickListener) {
((HistoryClickListener) getActivity()).historyClickClear();
}