Android getItemViewType（）在使用DSI将ListView上的图像和文本显示在不同行中时显示错误

我想为Android中的聊天应用程序创建一个ListView，在ListView中，如果用户键入文本，我想显示文本布局，如果用户发送图像，我想显示图像布局，我设计了两个布局，分别为sms_row.xml和sms_chat_row.xml，如果我只使用文本和图像，应用程序运行良好，通过手动将我的条件设置为true和false，但如果我试图动态地执行getItemViewType（int位置）显示错误和图像崩溃，下面是适配器类-->

DevAdapter.java

    package com.example.imageinsertdynamic;

import java.util.ArrayList;
import android.content.Context;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.LinearLayout.LayoutParams;

public class DevAdapter extends BaseAdapter {

    private ArrayList<Message> list;
    private Context mCont;
    LayoutParams lp;
    public Message ob;
    int type;

    public DevAdapter(Context context, ArrayList<Message> msg) {
        super();
        this.mCont = context;
        this.list = msg;
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

 @Override
     public int getViewTypeCount() {
         return 2;
     }

 @Override
 public int getItemViewType(int position) {
     if(true)//if ob.issetStatus() true if user types and image if user selects an image from the directory. but getting nullPointerException here.
     {
     return 0; 
     }
     else
     {
   return 1;
     } 
 }



    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ob=(Message) this.getItem(position);
        ViewHolder holder;
        type=getItemViewType(position);//1 for case one and 2 for case 2 , need getItemViewtype() to bring this 1 and 2 but app crashes doing so need help in this function only

        /*
         * 
         * ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         * 
         * HHHHHHHHEEEEEEEEEEEELLLLLLLLLLLPPPPPPPPPPP HERE !!
         * 
         * 
         * \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
         */

        if(convertView == null)
        {
            holder = new ViewHolder();
            switch (type) {
            case 0:
            convertView = LayoutInflater.from(mCont).inflate(R.layout.sms_row_chat, parent, false);
            holder.text = (TextView) convertView.findViewById(R.id.message_text);
            convertView.setTag(holder);
            break;
            case 1:
            convertView = LayoutInflater.from(mCont).inflate(R.layout.sms_row, parent, false);
            holder.message = (ImageView) convertView.findViewById(R.id.message);
            convertView.setTag(holder); 
        break;

            }
            }
        else
            holder = (ViewHolder) convertView.getTag();

        switch(type){
        case 0:
        holder.text.setText(ob.getmsg());
        System.out.println("value of isStatus image or text-->");
        lp = (LayoutParams) holder.text.getLayoutParams();
        break;
        case 1:
            holder.message.setImageBitmap(ob.getMessage());
            System.out.println("value of isStatus image or text-->");
            lp = (LayoutParams) holder.message.getLayoutParams();
            break;

        }
        //Check whether message is mine to show green background and align to right
            if(ob.isMine())
            {  switch(type){
            case 0:
                holder.text.setBackgroundResource(R.drawable.speech_bubble_orange);
                lp.gravity = Gravity.LEFT;
            break;
            case 1:
                holder.message.setBackgroundResource(R.drawable.speech_bubble_orange);
                lp.gravity = Gravity.LEFT;
                break;
            }
            }
            //If not mine then it is from sender to show orange background and align to left
            else
            {
                 switch(type){
                    case 0:
                holder.text.setBackgroundResource(R.drawable.speech_bubble_green);
                lp.gravity = Gravity.RIGHT;
                break;
                    case 1:
                        holder.message.setBackgroundResource(R.drawable.speech_bubble_green);
                        lp.gravity = Gravity.RIGHT;
                       break;
                 }
                 }
             switch(type){
                case 0:
            holder.text.setLayoutParams(lp);
            break;
                case 1:
                    holder.message.setLayoutParams(lp);
                    break;
             }
            //holder.message.setTextColor(R.color.textColor);   

        return convertView;
    }

    private static class ViewHolder
    {

        ImageView message;
        TextView text;
    }




    @Override
    public long getItemId(int arg0) {
        // TODO Auto-generated method stub
        return 0;
    }
}

package com.example.imageinsertdynamic;

import android.graphics.Bitmap;

public class Message {
    /**
     * The content of the message
     */
    Bitmap message;
    String msg;
    /**
     * boolean to determine, who is sender of this message
     */
    boolean isMine;
    /**
     * boolean to determine, whether the message is a status message or not.
     * it reflects the changes/updates about the sender is writing, have entered text etc
     */
    boolean isStatusMessage;

    /**
     * Constructor to make a Message object
     */
    public Message(Bitmap message, boolean isMine,boolean status) {
        super();
        this.message = message;
        this.isMine = isMine;
        this.isStatusMessage = status;
    }
    /**
     * Constructor to make a status Message object
     * consider the parameters are swaped from default Message constructor,
     *  not a good approach but have to go with it.
     */
    public Message(boolean status, String message,boolean isMine) {
        super();
        this.msg = message;
        this.isMine = isMine;
        this.isStatusMessage = status;
    }
    public Bitmap getMessage() {
        return message;
    }
    public void setMessage(Bitmap message) {
        this.message = message;
    }
    public String getmsg() {
        return msg;
    }
    public void setMessage(String text) {
        this.msg = text;
    }


    public boolean isMine() {
        return isMine;
    }
    public void setMine(boolean isMine) {
        this.isMine = isMine;
    }
    public boolean isStatusMessage() {
        return isStatusMessage;
    }
    public void setStatusMessage(boolean isStatusMessage) {
        this.isStatusMessage = isStatusMessage;
    }


}

isStatusMessage来自--> Message.java

    package com.example.imageinsertdynamic;

import java.util.ArrayList;
import android.content.Context;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.LinearLayout.LayoutParams;

public class DevAdapter extends BaseAdapter {

    private ArrayList<Message> list;
    private Context mCont;
    LayoutParams lp;
    public Message ob;
    int type;

    public DevAdapter(Context context, ArrayList<Message> msg) {
        super();
        this.mCont = context;
        this.list = msg;
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

 @Override
     public int getViewTypeCount() {
         return 2;
     }

 @Override
 public int getItemViewType(int position) {
     if(true)//if ob.issetStatus() true if user types and image if user selects an image from the directory. but getting nullPointerException here.
     {
     return 0; 
     }
     else
     {
   return 1;
     } 
 }



    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ob=(Message) this.getItem(position);
        ViewHolder holder;
        type=getItemViewType(position);//1 for case one and 2 for case 2 , need getItemViewtype() to bring this 1 and 2 but app crashes doing so need help in this function only

        /*
         * 
         * ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         * 
         * HHHHHHHHEEEEEEEEEEEELLLLLLLLLLLPPPPPPPPPPP HERE !!
         * 
         * 
         * \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
         */

        if(convertView == null)
        {
            holder = new ViewHolder();
            switch (type) {
            case 0:
            convertView = LayoutInflater.from(mCont).inflate(R.layout.sms_row_chat, parent, false);
            holder.text = (TextView) convertView.findViewById(R.id.message_text);
            convertView.setTag(holder);
            break;
            case 1:
            convertView = LayoutInflater.from(mCont).inflate(R.layout.sms_row, parent, false);
            holder.message = (ImageView) convertView.findViewById(R.id.message);
            convertView.setTag(holder); 
        break;

            }
            }
        else
            holder = (ViewHolder) convertView.getTag();

        switch(type){
        case 0:
        holder.text.setText(ob.getmsg());
        System.out.println("value of isStatus image or text-->");
        lp = (LayoutParams) holder.text.getLayoutParams();
        break;
        case 1:
            holder.message.setImageBitmap(ob.getMessage());
            System.out.println("value of isStatus image or text-->");
            lp = (LayoutParams) holder.message.getLayoutParams();
            break;

        }
        //Check whether message is mine to show green background and align to right
            if(ob.isMine())
            {  switch(type){
            case 0:
                holder.text.setBackgroundResource(R.drawable.speech_bubble_orange);
                lp.gravity = Gravity.LEFT;
            break;
            case 1:
                holder.message.setBackgroundResource(R.drawable.speech_bubble_orange);
                lp.gravity = Gravity.LEFT;
                break;
            }
            }
            //If not mine then it is from sender to show orange background and align to left
            else
            {
                 switch(type){
                    case 0:
                holder.text.setBackgroundResource(R.drawable.speech_bubble_green);
                lp.gravity = Gravity.RIGHT;
                break;
                    case 1:
                        holder.message.setBackgroundResource(R.drawable.speech_bubble_green);
                        lp.gravity = Gravity.RIGHT;
                       break;
                 }
                 }
             switch(type){
                case 0:
            holder.text.setLayoutParams(lp);
            break;
                case 1:
                    holder.message.setLayoutParams(lp);
                    break;
             }
            //holder.message.setTextColor(R.color.textColor);   

        return convertView;
    }

    private static class ViewHolder
    {

        ImageView message;
        TextView text;
    }




    @Override
    public long getItemId(int arg0) {
        // TODO Auto-generated method stub
        return 0;
    }
}

package com.example.imageinsertdynamic;

import android.graphics.Bitmap;

public class Message {
    /**
     * The content of the message
     */
    Bitmap message;
    String msg;
    /**
     * boolean to determine, who is sender of this message
     */
    boolean isMine;
    /**
     * boolean to determine, whether the message is a status message or not.
     * it reflects the changes/updates about the sender is writing, have entered text etc
     */
    boolean isStatusMessage;

    /**
     * Constructor to make a Message object
     */
    public Message(Bitmap message, boolean isMine,boolean status) {
        super();
        this.message = message;
        this.isMine = isMine;
        this.isStatusMessage = status;
    }
    /**
     * Constructor to make a status Message object
     * consider the parameters are swaped from default Message constructor,
     *  not a good approach but have to go with it.
     */
    public Message(boolean status, String message,boolean isMine) {
        super();
        this.msg = message;
        this.isMine = isMine;
        this.isStatusMessage = status;
    }
    public Bitmap getMessage() {
        return message;
    }
    public void setMessage(Bitmap message) {
        this.message = message;
    }
    public String getmsg() {
        return msg;
    }
    public void setMessage(String text) {
        this.msg = text;
    }


    public boolean isMine() {
        return isMine;
    }
    public void setMine(boolean isMine) {
        this.isMine = isMine;
    }
    public boolean isStatusMessage() {
        return isStatusMessage;
    }
    public void setStatusMessage(boolean isStatusMessage) {
        this.isStatusMessage = isStatusMessage;
    }


}

---

返回0和1，而不是返回1和2。它类似于数组的索引。如果创建两个位置的数组并尝试访问数组[2]，则会得到ArrayIndexOutBoundException。这几乎就是发生在你身上的事情

@Override
 public int getItemViewType(int position) {
     if(true)//if ob.issetStatus() true if user types and image if user selects an image from the directory. but getting nullPointerException here.
     {
       return 0; 
     }
     else
     {
       return 1;
     } 

编辑：

---

通常情况下，条件与数据集相关联（

ArrayList

）。getItemViewType将位置作为参数。因此，您必须在该位置检索项目，并检查是否满足条件，而不是返回1和2，而是返回0和1。它类似于数组的索引。如果创建两个位置的数组并尝试访问数组[2]，则会得到ArrayIndexOutBoundException。这几乎就是发生在你身上的事情

@Override
 public int getItemViewType(int position) {
     if(true)//if ob.issetStatus() true if user types and image if user selects an image from the directory. but getting nullPointerException here.
     {
       return 0; 
     }
     else
     {
       return 1;
     } 

编辑：

---

通常情况下，条件与数据集相关联（

ArrayList

）。getItemViewType将位置作为参数。因此，您必须在该位置检索项目，并检查是否满足条件

您可以将文本和图像组件添加到listview组件中。您需要哪一个，将其设置为visibility true并指定值。您在getItemViewType（int位置）中观察到了什么错误？你如何“动态地”改变它？。可以help@sandrstar我在getView方法中设置type=getItemViewType（position），但得到空点异常错误。这样，我在messsage.java类中有一个isstatusmessage，它检查它是否是文本或图像，并将其设置为true和false。您可以将文本和图像组件添加到listview组件中。您需要哪一个，将其设置为visibility true并指定值。您在getItemViewType（int位置）中观察到了什么错误？你如何“动态地”改变它？。可以help@sandrstar我在getView方法中设置type=getItemViewType（position），但是得到nullpointerexception错误。这样做，我在Message.java类中有一个isstatusmessage，它检查它是否是文本或图像，并将其设置为true和false。这也没有帮助，它仍然显示nullpointerexception，我使用int type=getItemView（位置）在getView方法中，类型在选择案例的开关（类型）中，手动将其保留为1，2提供所需的结果。我能做什么？您是在getView中更改案例常量，还是像以前一样保留它（1和2）？duuhh我想我不应该再做程序员了，我想自杀，非常感谢它现在可以工作了，但是我怎么能动态地把if语句设置为true-false呢？怎么设置呢，你帮了大忙了？你能重新定义最后一个吗？什么是“if语句true-false dinamically”的意思？getItemViewType（int位置）中的if语句，具有if（true）返回0；else返回1；现在，我希望true仅在它是文本消息时为true，如果它是图像时为false，但我的ob=（message）new getItem（position）ob是消息类型的对象吗，我想要ob.isStatusMessage，如果它是图像和文本，则返回true和false，如果它在getView中初始化，如何在getitemViewType中使用它？这也没有帮助，它仍然显示nullpointerexception，我在getView方法中使用int type=getItemView（position），类型在开关（type）中它选择案例，手动将其保留为1，2将提供所需的结果。我能做什么？您是在getView中更改了案例常量，还是像以前一样保留它（1和2）？duuhh我想我不应该再做程序员了，我想自杀，非常感谢它现在可以工作了，但是我怎么能动态地把if语句设置为true-false呢？怎么设置呢，你帮了大忙了？你能重新定义最后一个吗？什么是“if语句true-false dinamically”的意思？getItemViewType（int位置）中的if语句，具有if（true）返回0；else返回1；现在，我希望true仅在它是文本消息时为true，如果它是图像时为false，但我的ob=（message）new getItem（position）ob是消息类型的对象吗？我想要ob.isStatusMessage，如果它是图像和文本，则返回true和false。如果它在getView中初始化，如何在getitemViewType中使用它？