探究Android中ListView復用導致布局錯亂的解決方案

首先來說一下具體的需求是什麼樣的：

需求如圖所示，這裡面有ABCD四個選項的題目，當點擊A選項，如果A是正確的答案，則變成對勾的圖案，如果是錯誤答案，則變成錯誤的圖案，這裡當時在寫的時候覺得很簡單，只要是在點擊的時候判斷我點擊的選項與正確答案是否一樣，是一樣就將圖片換成正確的樣式，如果不一樣就換成錯誤的樣式，於是我便寫了下面的代碼(只貼出了核心Adapter中的代碼)

package com.fizzer.anbangproject_dahuo_test.Adapter; 
import android.annotation.TargetApi; 
import android.content.Context; 
import android.graphics.drawable.Drawable; 
import android.os.Build; 
import android.text.TextUtils; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.TextView; 
import com.fizzer.anbangproject_dahuo_test.Model.ConvertModel; 
import com.fizzer.anbangproject_dahuo_test.R; 
import java.util.List; 
/** 
* Created by Fizzer on 2016/10/8. 
* Email: [email protected] 
*/ 
public class ConvertViewAdapter extends BaseAdapter { 
private List<ConvertModel> list; 
private Context mContext; 
public ConvertViewAdapter(Context context, List<ConvertModel> list) { 
mContext = context; 
this.list = list; 
} 
@Override 
public int getCount() { 
if (list == null) { 
return 0; 
} else { 
return list.size(); 
} 
} 
@Override 
public View getView(int position, View convertView, ViewGroup parent) { 
ViewHolder mViewHolder; 
if (convertView == null) { 
convertView = View.inflate(mContext, R.layout.view_upgradepartnet_topic_layout, null); 
mViewHolder = new ViewHolder(); 
mViewHolder.tvTitle = (TextView) convertView.findViewById(R.id.tvTitle); 
mViewHolder.tvSelectA = (TextView) convertView.findViewById(R.id.tvSelectA); 
mViewHolder.tvSelectB = (TextView) convertView.findViewById(R.id.tvSelectB); 
mViewHolder.tvSelectC = (TextView) convertView.findViewById(R.id.tvSelectC); 
mViewHolder.tvSelectD = (TextView) convertView.findViewById(R.id.tvSelectD); 
convertView.setTag(mViewHolder); 
} else { 
mViewHolder = (ViewHolder) convertView.getTag(); 
} 
ConvertModel module = list.get(position); 
mViewHolder.tvTitle.setText("Q" + (position + 1) + ":" + module.title); 
mViewHolder.tvSelectA.setText(module.optionA); 
mViewHolder.tvSelectB.setText(module.optionB); 
mViewHolder.tvSelectC.setText(module.optionC); 
mViewHolder.tvSelectD.setText(module.optionD); 
initListener(mViewHolder, module.rightOption, position, module); 
return convertView; 
} 
@Override 
public Object getItem(int position) { 
return null; 
} 
@Override 
public long getItemId(int position) { 
return 0; 
} 
private void initListener(final ViewHolder mViewHolder, final String select, final int position, final ConvertModel module) { 
mViewHolder.tvSelectA.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
judgeSelect(mViewHolder, mViewHolder.tvSelectA, "A", select, position); 
} 
}); 
mViewHolder.tvSelectB.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
judgeSelect(mViewHolder, mViewHolder.tvSelectB, "B", select, position); 
} 
}); 
mViewHolder.tvSelectC.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
judgeSelect(mViewHolder, mViewHolder.tvSelectC, "C", select, position); 
} 
}); 
mViewHolder.tvSelectD.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
judgeSelect(mViewHolder, mViewHolder.tvSelectD, "D", select, position); 
} 
}); 
} 
private void clearSelectState(ViewHolder mViewHolder) { 
mViewHolder.tvSelectA.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_a), null, null, null); 
mViewHolder.tvSelectB.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_b), null, null, null); 
mViewHolder.tvSelectC.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_c), null, null, null); 
mViewHolder.tvSelectD.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_d), null, null, null); 
} 
private void judgeSelect(ViewHolder viewHolder, TextView text, String select, String rightSelect, int position) { 
//清楚之前的狀態 
clearSelectState(viewHolder); 
if (select.equals(rightSelect)) { 
text.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_right), null, null, null); 
} else { 
text.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_error), null, null, null); 
} 
} 
@TargetApi(Build.VERSION_CODES.LOLLIPOP) 
private Drawable getDrawableResource(int res) { 
Drawable drawable = mContext.getDrawable(res); 
drawable.setBounds(0, 0, drawable.getMinimumWidth(), drawable.getMinimumHeight()); 
return drawable; 
} 
class ViewHolder { 
TextView tvTitle; 
TextView tvSelectA; 
TextView tvSelectB; 
TextView tvSelectC; 
TextView tvSelectD; 
} 
}

寫完這段代碼信心滿滿，覺得沒問題了，但是在手機上一運行，發現出問題了，效果如下：

是的，由於listview的布局復用機制，導致下面沒有選擇的條目也因為復用而選擇了選項

其實解決的方法很簡單，就是將這個選中的條目與該條目對應的model相關聯起來，具體怎麼做呢，下面來仔細的分析分析，

首先在創建model的時候添加一個默認的字段，這個字段就是你選擇的選項，當然初始值是沒有的，在getView中對布局進行初始化的時候，就去判斷這個字段是否有值，並且值為多少，如果有值，就去判斷值為正確還是為錯誤，為正確則替換成正確的圖片，如果為錯誤，則替換成錯誤的圖片，如果沒有值，則顯示原始的ABCD四種初始化圖片，這樣，問題就迎刃而解了

下面貼出完整的代碼，其實就跟上面的代碼是差不多的，只不過在對model中添加的那個字段進行了一些復制與判斷

package com.fizzer.anbangproject_dahuo_test.Adapter; 
import android.annotation.TargetApi; 
import android.content.Context; 
import android.graphics.drawable.Drawable; 
import android.os.Build; 
import android.text.TextUtils; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.TextView; 
import com.fizzer.anbangproject_dahuo_test.Model.ConvertModel; 
import com.fizzer.anbangproject_dahuo_test.R; 
import java.util.List; 
/** 
* Created by Fizzer on 2016/10/8. 
* Email: [email protected] 
*/ 
public class ConvertViewAdapter extends BaseAdapter { 
private List<ConvertModel> list; 
private Context mContext; 
public ConvertViewAdapter(Context context, List<ConvertModel> list) { 
mContext = context; 
this.list = list; 
} 
@Override 
public int getCount() { 
if (list == null) { 
return 0; 
} else { 
return list.size(); 
} 
} 
@Override 
public View getView(int position, View convertView, ViewGroup parent) { 
ViewHolder mViewHolder; 
if (convertView == null) { 
convertView = View.inflate(mContext, R.layout.view_upgradepartnet_topic_layout, null); 
mViewHolder = new ViewHolder(); 
mViewHolder.tvTitle = (TextView) convertView.findViewById(R.id.tvTitle); 
mViewHolder.tvSelectA = (TextView) convertView.findViewById(R.id.tvSelectA); 
mViewHolder.tvSelectB = (TextView) convertView.findViewById(R.id.tvSelectB); 
mViewHolder.tvSelectC = (TextView) convertView.findViewById(R.id.tvSelectC); 
mViewHolder.tvSelectD = (TextView) convertView.findViewById(R.id.tvSelectD); 
convertView.setTag(mViewHolder); 
} else { 
mViewHolder = (ViewHolder) convertView.getTag(); 
} 
ConvertModel module = list.get(position); 
mViewHolder.tvTitle.setText("Q" + (position + 1) + ":" + module.title); 
mViewHolder.tvSelectA.setText(module.optionA); 
mViewHolder.tvSelectB.setText(module.optionB); 
mViewHolder.tvSelectC.setText(module.optionC); 
mViewHolder.tvSelectD.setText(module.optionD); 
initListener(mViewHolder, module.rightOption, position, module); 
<span >if (TextUtils.isEmpty(module.check)) { 
clearSelectState(mViewHolder); 
} else { 
judgeSelect(mViewHolder, getCheckTextView(mViewHolder, module.check), module.check, module.rightOption, position); 
}</span> 
return convertView; 
} 
@Override 
public Object getItem(int position) { 
return null; 
} 
@Override 
public long getItemId(int position) { 
return 0; 
} 
private void initListener(final ViewHolder mViewHolder, final String select, final int position, final ConvertModel module) { 
mViewHolder.tvSelectA.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
<span >module.check = "A";</span> 
judgeSelect(mViewHolder, mViewHolder.tvSelectA, "A", select, position); 
} 
}); 
mViewHolder.tvSelectB.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
<span >module.check = "B";</span> 
judgeSelect(mViewHolder, mViewHolder.tvSelectB, "B", select, position); 
} 
}); 
mViewHolder.tvSelectC.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
<span >module.check = "C"; 
</span> judgeSelect(mViewHolder, mViewHolder.tvSelectC, "C", select, position); 
} 
}); 
mViewHolder.tvSelectD.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
<span >module.check = "D";</span> 
judgeSelect(mViewHolder, mViewHolder.tvSelectD, "D", select, position); 
} 
}); 
} 
private void clearSelectState(ViewHolder mViewHolder) { 
mViewHolder.tvSelectA.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_a), null, null, null); 
mViewHolder.tvSelectB.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_b), null, null, null); 
mViewHolder.tvSelectC.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_c), null, null, null); 
mViewHolder.tvSelectD.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_d), null, null, null); 
} 
private void judgeSelect(ViewHolder viewHolder, TextView text, String select, String rightSelect, int position) { 
//清楚之前的狀態 
clearSelectState(viewHolder); 
if (select.equals(rightSelect)) { 
text.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_right), null, null, null); 
} else { 
text.setCompoundDrawables(getDrawableResource(R.drawable.ic_select_error), null, null, null); 
} 
} 
@TargetApi(Build.VERSION_CODES.LOLLIPOP) 
private Drawable getDrawableResource(int res) { 
Drawable drawable = mContext.getDrawable(res); 
drawable.setBounds(0, 0, drawable.getMinimumWidth(), drawable.getMinimumHeight()); 
return drawable; 
} 
<span >private TextView getCheckTextView(ViewHolder mViewHolder, String rightSelect) { 
if ("A".equals(rightSelect)) { 
return mViewHolder.tvSelectA; 
} else if ("B".equals(rightSelect)) { 
return mViewHolder.tvSelectB; 
} else if ("C".equals(rightSelect)) { 
return mViewHolder.tvSelectC; 
} else if ("D".equals(rightSelect)) { 
return mViewHolder.tvSelectD; 
} 
return null; 
}</span> 
class ViewHolder { 
TextView tvTitle; 
TextView tvSelectA; 
TextView tvSelectB; 
TextView tvSelectC; 
TextView tvSelectD; 
} 
}

其中標紅的就是新添的代碼，加上這些後，問題就解決了，來看一下解決後的代碼運行情況：

總結：

最後來總結一下這個問題的解決思路吧：

首先就是需要在該填充器對應的實體類中添加一個選中的(check)字段，在進行getview操作中，去根據這個check字段來進行相應的操作，如過有值，則設置成對應的樣式，如果沒有值，則設置成沒有值得樣式，當然，在用戶點擊的時候，要及時的對該字段進行賦值，類似的，像Listview中有checkbox也可以采用同樣的方法來進行解決。

以上所述是小編給大家介紹的探究Android中ListView復用導致布局錯亂的解決方案，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復大家的。在此也非常感謝大家對本站網站的支持！