在QQ群裡有一位朋友提出想實作這種效果:他的viewpager的每個page是一個fragment,假設有兩個page,每個page上有一個按鈕,當滑動到第page2後,按下page2頁面上按鈕時不需要退出整個activity,而是退到page1,再點選page1的按鈕,才推出activity,同理,在點選手機後退鍵的時候需實作相同效果。
我本身是一個菜,經常關注qq群裡其他人的提問,因為看别人提問,會想想自己是不是在遇到相同問題時有思路去獨立解決,看别人回答,會知道自己的思路是否正确。我想這個是進步的一個有效方法。于是我就想嘗試幫他解決。
最後我是這樣解決的:
-------- 接口-------
package com.example.buxiaohui.myapplication2;
/**
* Created by buxiaohui on 2/26/15.
*/
public interface FragmentCallback {
public void back(int index);
}
-------- Activity-------
package com.example.buxiaohui.myapplication2;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.view.ViewGroup;
import java.util.ArrayList;
import android.support.v4.app.FragmentActivity;
public class MainActivity extends FragmentActivity implements FragmentCallback{
ViewPager mViewPager;
ArrayList<Fragment> fragmentList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager = (ViewPager)findViewById(R.id.pager);
fragmentList = new ArrayList<Fragment>();
FragmentOne fragmentOne = new FragmentOne();
FragmentTwo fragmentTwo = new FragmentTwo();
fragmentTwo.setFragmentCallback(this);
fragmentOne.setFragmentCallback(this);
fragmentList.add(fragmentOne);
fragmentList.add(fragmentTwo);
mViewPager.setAdapter(new MyFrageStatePagerAdapter(getSupportFragmentManager()));
}
public class MyFrageStatePagerAdapter extends FragmentStatePagerAdapter{
public MyFrageStatePagerAdapter(FragmentManager fm)
{
super(fm);
}
@Override
public Fragment getItem(int position) {
return fragmentList.get(position);
}
@Override
public int getCount() {
return fragmentList.size();
}
@Override
public void finishUpdate(ViewGroup container)
{
super.finishUpdate(container);
}
}
@Override
public void onBackPressed() {
if(mViewPager.getCurrentItem()==1){
mViewPager.setCurrentItem(0);
}else{
this.finish();
}
}
@Override
public void back(int index) {
if(index==1){
mViewPager.setCurrentItem(0);
}
else{
this.finish();
}
}
}
-------- Fragment 1-------
package com.example.buxiaohui.myapplication2;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
/**
* Created by buxiaohui on 2/26/15.
*/
public class FragmentOne extends Fragment {
private FragmentCallback fragmentCallback;
private void callBack(int index){
this.fragmentCallback.back(index);
}
public void setFragmentCallback(FragmentCallback fragmentCallback){
this.fragmentCallback = fragmentCallback;
}
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_one, container, false);
}
@Override
public void onViewCreated(View view, Bundle bundle) {
Button button = (Button)view.findViewById(R.id.b1);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
callBack( 0);
}
});
}
}
-------- Fragment 2-------
package com.example.buxiaohui.myapplication2;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
/**
* Created by buxiaohui on 2/26/15.
*/
public class FragmentTwo extends Fragment {
private FragmentCallback fragmentCallback;
private void callBack(int index){
this.fragmentCallback.back(index);
}
public void setFragmentCallback(FragmentCallback fragmentCallback){
this.fragmentCallback = fragmentCallback;
}
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_two, container, false);
}
@Override
public void onViewCreated(View view, Bundle bundle) {
Button button = (Button)view.findViewById(R.id.b2);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
callBack(1);
}
});
}
}
activity的xml包含一個viewpager,兩個fragment的xml各自隻包含一個button。有點基礎的話代碼稍微看下就懂了。
可以建個工程然後copy一下試試看效果。另外,demo寫的太簡單了,沒有資料和其他布局,是以我不清楚我的寫法會不會導緻由page2回到page1時page1的資料或者頁面出問題。