如何使用 ViewPager 实现视图更改条件

Posted 2023-02-26

【中文标题】如何使用 ViewPager 实现视图更改条件

【英文标题】：How to implement condition on view change using ViewPager

【发布时间】：2014-08-30 05:07:37

【问题描述】：

在我的程序中，我使用Fragments with ViewPager，其中每个Fragment 都包含3 checkboxes，如果用户没有checked 任何checkbox，我想put a condition 不要切换到other fragment 当swipe.

我知道condition 可能是什么，但我不知道where to put？

这个condition 对我来说是work，但是where to use 不知道：

if(!cb1.isChecked() && !cb2.isChecked() && !cb3.isChecked())
            
                Toast.makeText(getActivity(), "Choose any one !", Toast.LENGTH_SHORT).show();
                return view;
            

MainActivity.java:-

public class MainActivity extends FragmentActivity 

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        // Get the view from activity_main.xml
        setContentView(R.layout.activity_main);

        // Locate the viewpager in activity_main.xml
        ViewPager viewPager = (ViewPager) findViewById(R.id.pager);

        // Set the ViewPagerAdapter into ViewPager
        viewPager.setAdapter(new ViewPagerAdapter(getSupportFragmentManager()));

    

ViewPagerAdapter.java:-

public class ViewPagerAdapter extends FragmentPagerAdapter 

    final int PAGE_COUNT = 2;
    // Tab Titles
    private String tabtitles[] = new String[]  
            "Fragment 1",
            "Fragment 2"
            ;

    Context context;

    public ViewPagerAdapter(FragmentManager fm) 
        super(fm);
    

    @Override
    public int getCount() 
        return PAGE_COUNT;
    

    @Override
    public Fragment getItem(int position) 
        switch (position) 

            // Open FragmentTab1.java
        case 0:
            FragmentTab1 fragmenttab1 = new FragmentTab1();
            return fragmenttab1;

            // Open FragmentTab2.java
        case 1:
            FragmentTab2 fragmenttab2 = new FragmentTab2();
            return fragmenttab2;

        
        return null;
    

    @Override
    public CharSequence getPageTitle(int position) 
        return tabtitles[position];
    

FragmentTab1.java:-

public class FragmentTab1 extends Fragment 

    View view;
    CheckBox cb1, cb2, cb3;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) 
        // Get the view from fragmenttab1.xml
        view = inflater.inflate(R.layout.fragmenttab1, container, false);

        cb1 = (CheckBox) view.findViewById(R.id.cb1);
        cb2 = (CheckBox) view.findViewById(R.id.cb2);
        cb3 = (CheckBox) view.findViewById(R.id.cb3);

        // control status of body frame checkboxes
        cb1.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() 

           @Override
           public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) 
                // TODO Auto-generated method stub
                if(isChecked)
                    cb2.setChecked(false);
                    cb3.setChecked(false);      
                
            
        );

        cb2.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() 

            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) 
                // TODO Auto-generated method stub
                if(isChecked)
                    cb1.setChecked(false);
                    cb3.setChecked(false);
                
            
        );

        cb3.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() 

            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) 
                // TODO Auto-generated method stub
                if(isChecked)
                    cb1.setChecked(false);
                    cb2.setChecked(false);
                
            
        );         

    /** 
    **  if(!cb1.isChecked() && !cb2.isChecked() && !cb3.isChecked())
        
            Toast.makeText(getActivity(), "Choose any one !", Toast.LENGTH_SHORT).show();
            return view;
        
    ***/    

        return view;
    

【问题讨论】：

不确定...试试OnPageChangeListener..

【参考方案1】：

更好的办法是禁用 viewpager 滑动，然后再次允许它，因此创建自定义一个并使用方法 setPagingEnabled(boolean enabled)

public class CustomViewPager extends ViewPager 

private boolean enabled;

public CustomViewPager(Context context, AttributeSet attrs) 
    super(context, attrs);
    this.enabled = true;


@Override
public boolean onTouchEvent(MotionEvent event) 
    if (this.enabled) 
        return super.onTouchEvent(event);
    

    return false;


@Override
public boolean onInterceptTouchEvent(MotionEvent event) 
    if (this.enabled) 
        return super.onInterceptTouchEvent(event);
    

    return false;


public void setPagingEnabled(boolean enabled) 
    this.enabled = enabled;
 

在你的xml中你需要：

<mypackage.CustomViewPager 
android:id="@+id/myViewPager" 
android:layout_ 
android:layout_ />

参考： （我相信版权:-)）

How do disable paging by swiping with finger in ViewPager but still be able to swipe programmatically?