刚接触fragment，之前在书上看的时候，由于它当时是加上了背景颜色，所以在切换的时候我没有去注意到重叠的问题。然后最近在做一个项目的时候用到fragment，才发现了这个问题。

我用RadioGroup里的RadioButton来做切换

package com.moke.activity;

public class CJD_CardPackageActivity extends Activity implements OnCheckedChangeListener {
    
    private RadioGroup radipGroup;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.cjd_cardpackageactivity);
    
        init();
        
    }
    
    
    private void init() {
        radipGroup = (RadioGroup)findViewById(R.id.cjd_CardPackageActivity_rgp);
        bindClick();
        
    }    
    
    private void bindClick(){
        radipGroup.setOnCheckedChangeListener(this);
    }

    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
        // TODO Auto-generated method stub
        
        CJD_Fragment_CardPackageUnused unusedFragment = new CJD_Fragment_CardPackageUnused();
        CJD_Fragment_CardPackageUsed usedFragment = new CJD_Fragment_CardPackageUsed();
        FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction transaction = fragmentManager.beginTransaction();
        
        switch (checkedId) {
        //切换到未使用页面
        case R.id.cjd_CardPackageActivity_rbtn_unused:
            transaction.replace(R.id.cjd_CardPackageActivity_fl_switch, unusedFragment);
            transaction.commit();
            break;
        //切换到使用页面
        case R.id.cjd_CardPackageActivity_rbtn_used:
            transaction.replace(R.id.cjd_CardPackageActivity_fl_switch, usedFragment);
            transaction.commit();
            break;
        default:
            break;
        }
        
    }
}

布局文件的代码cjd_cardpackageactivity.xml：

一开始“未使用”的界面：

切换到“已使用”界面

切换回“未使用”界面并向下活动：

这样就发现新的重叠在了原来的Fragment上，当然原来的Fragment是固定不动的，还保留着当时的位置。

这是修改后的代码，目前从效果上看已经没有了重叠的现象了，非常感谢“li21”！！

public class CJD_CardPackageActivity extends Activity implements OnCheckedChangeListener {
    
    private RadioGroup radipGroup;
    private FragmentTransaction transaction;
    private CJD_Fragment_CardPackageUnused unusedFragment;
    private CJD_Fragment_CardPackageUsed usedFragment;
    private FragmentManager fragmentManager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.cjd_cardpackageactivity);
        
        init();
        
    }
    
    
    private void init() {
        radipGroup = (RadioGroup)findViewById(R.id.cjd_CardPackageActivity_rgp);
        unusedFragment = new CJD_Fragment_CardPackageUnused();
        usedFragment = new CJD_Fragment_CardPackageUsed();        
        fragmentManager = getFragmentManager();
        
//        unusedFragment = (CJD_Fragment_CardPackageUnused) getFragmentManager().findFragmentByTag("unused");
//        usedFragment = (CJD_Fragment_CardPackageUsed) getFragmentManager().findFragmentByTag("used");
        transaction = fragmentManager.beginTransaction();
        transaction.add(R.id.cjd_CardPackageActivity_fl_switch, unusedFragment).commit();
        bindClick();
        
    }    
    
    private void bindClick(){
        radipGroup.setOnCheckedChangeListener(this);
    }

    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
        // TODO Auto-generated method stub

        switch (checkedId) {
        //切换到未使用页面
        case R.id.cjd_CardPackageActivity_rbtn_unused:
            
            transaction = fragmentManager.beginTransaction();
            transaction.replace(R.id.cjd_CardPackageActivity_fl_switch, unusedFragment);
            transaction.commit();
            break;
        //切换到使用页面
        case R.id.cjd_CardPackageActivity_rbtn_used:
            
            transaction = fragmentManager.beginTransaction();
            transaction.replace(R.id.cjd_CardPackageActivity_fl_switch, usedFragment);
            transaction.commit();
            break;
        default:
            break;
        }
        
    }
         
}

我把布局里的fragment删掉了，然后在一开始的时候把unusedFragment add上去。接下来的工作应该是我要去试一下fragment的切换过程中会不会重新加载这样的问题，找到了一些有关hide()和show()的东西。