Android中ListView复用导致布局错乱的解决方案

其他 2018-08-09 20:16:20 阅读次数: 0

首先来说一下具体的需求是什么样的：


需求如图所示，这里面有ABCD四个选项的题目，当点击A选项，如果A是正确的答案，则变成对勾的图案，如果是错误答案，则变成错误的图案，

这里当时在写的时候觉得很简单，只要是在点击的时候判断我点击的选项与正确答案是否一样，是一样就将图片换成正确的样式，如果不一样就换成错误的样式，于是我便写了下面的代码(只贴出了核心Adapter中的代码)

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) {
        //清楚之前的状态
        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;
    }

}
写完这段代码信心满满，觉得没问题了，但是在手机上一运行，发现出问题了，效果如下：



是的，由于listview的布局复用机制，导致下面没有选择的条目也因为复用而选择了选项

其实解决的方法很简单，就是将这个选中的条目与该条目对应的model相关联起来，具体怎么做呢，下面来仔细的分析分析，

首先在创建model的时候添加一个默认的字段，这个字段就是你选择的选项，当然初始值是没有的，在getView中对布局进行初始化的时候，就去判断这个字段是否有值，并且值为多少，如果有值，就去判断值为正确还是为错误，为正确则替换成正确的图片，如果为错误，则替换成错误的图片，如果没有值，则显示原始的ABCD四种初始化图片，这样，问题就迎刃而解了

下面贴出完整的代码，其实就跟上面的代码是差不多的，只不过在对model中添加的那个字段进行了一些复制与判断

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 style="color:#cc0000;">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 style="color:#cc0000;">module.check = "A";</span>
                judgeSelect(mViewHolder, mViewHolder.tvSelectA, "A", select, position);
            }
        });

        mViewHolder.tvSelectB.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                <span style="color:#cc0000;">module.check = "B";</span>
                judgeSelect(mViewHolder, mViewHolder.tvSelectB, "B", select, position);
            }
        });

        mViewHolder.tvSelectC.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                <span style="color:#cc0000;">module.check = "C";
</span>                judgeSelect(mViewHolder, mViewHolder.tvSelectC, "C", select, position);
            }
        });

        mViewHolder.tvSelectD.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                <span style="color:#cc0000;">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) {
        //清楚之前的状态
        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 style="color:#cc0000;">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;
    }

}

其中标红的就是新添的代码，加上这些后，问题就解决了，来看一下解决后的代码运行情况：



总结：

最后来总结一下这个问题的解决思路吧：

首先就是需要在该填充器对应的实体类中添加一个选中的(check)字段，在进行getview操作中，去根据这个check字段来进行相应的操作，如过有值，则设置成对应的样式，如果没有值，则设置成没有值得样式，当然，在用户点击的时候，要及时的对该字段进行赋值，类似的，像Listview中有checkbox也可以采用同样的方法来进行解决




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