将图像（表情符号）放在ListView上

我想为我的聊天添加新功能。我有一个代码，允许我插入聊天气泡，它的工作非常好（1，2）。我试图制作消息和适配器（对于图像）类，类似于以前的适配器和消息（对于文本）类。我希望它不像Messenger那样工作。当消息框为空时，发送按钮是表情按钮，它应该在ListView上放置一个表情符号（我会在按下的长度内跳过增加表情大小）。当消息框中有文本时，图释按钮将变为发送按钮，并且此按钮应将该框的内容放在ListView上。我尝试过，但我试过的一切，失败（当我把setAdapter TextChangedListener的按钮什么也不做，当我严格设置setAdapter到emojiAdapter Android Studio会抛出我空指针异常）。下面是我的代码：将图像（表情符号）放在ListView上

错误日志：

E/AndroidRuntime: FATAL EXCEPTION: main 
       Process: com.bk.cryptit, PID: 2720 
       java.lang.NullPointerException 
        at com.bk.cryptit.Chats.sendEmojiMessage(Chats.java:115) 
        at com.bk.cryptit.Chats$2.onClick(Chats.java:77) 
        at android.view.View.performClick(View.java:4438) 
        at android.view.View$PerformClick.run(View.java:18422) 
        at android.os.Handler.handleCallback(Handler.java:733) 
        at android.os.Handler.dispatchMessage(Handler.java:95) 
        at android.os.Looper.loop(Looper.java:136) 
        at android.app.ActivityThread.main(ActivityThread.java:5017) 
        at java.lang.reflect.Method.invokeNative(Native Method) 
        at java.lang.reflect.Method.invoke(Method.java:515) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
        at dalvik.system.NativeStart.main(Native Method) 
Application terminated.

ChatMessage.java

package com.bk.cryptit; 

import java.util.Random; 

public class ChatMessage { 

public String body, sender, receiver, senderName; 
public String Date, Time; 
public String msgid; 
public boolean isMine; 

public ChatMessage(String Sender, String Receiver, String messageString, 
        String ID, boolean isMINE) { 
    body = messageString; 
    isMine = isMINE; 
    sender = Sender; 
    msgid = ID; 
    receiver = Receiver; 
    senderName = sender; 
} 

public void setMsgID() { 

    msgid += "-" + String.format("%02d", new Random().nextInt(100)); 
    ; 
} 
}

ChatAdapter.java

package com.bk.cryptit; 

import java.util.ArrayList; 

import android.app.Activity; 
import android.content.Context; 
import android.graphics.Color; 
import android.text.InputFilter; 
import android.util.Log; 
import android.view.Gravity; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.LinearLayout; 
import android.widget.TextView; 
import java.util.ArrayList; 

import static android.R.id.list; 

public class ChatAdapter extends BaseAdapter { 

private static LayoutInflater inflater = null; 
ArrayList<ChatMessage> chatMessageList; 

public ChatAdapter(Activity activity, ArrayList<ChatMessage> list) { 
    chatMessageList = list; 
    inflater = (LayoutInflater) activity 
      .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 

} 

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

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

@Override 
public long getItemId(int position) { 
    return position; 
} 

@Override 
public View getView(int position, View convertView, ViewGroup parent) { 
    ChatMessage message = (ChatMessage) chatMessageList.get(position); 
    View vi = convertView; 
    if (convertView == null) 
     vi = inflater.inflate(R.layout.chatbubble, null); 

    TextView msg = (TextView) vi.findViewById(R.id.message_text); 
    msg.setText(message.body); 
    msg.setTextSize(16); 
    msg.setSingleLine(false); 
    LinearLayout layout = (LinearLayout) vi 
      .findViewById(R.id.bubble_layout); 
    LinearLayout parent_layout = (LinearLayout) vi 
      .findViewById(R.id.bubble_layout_parent); 
    layout.setPadding(15,11,15,15); 

    // if message is mine then align to right 
    if (message.isMine) { 
     layout.setBackgroundResource(R.drawable.chat_bubble_right); 
     parent_layout.setGravity(Gravity.RIGHT); 
    } 
    // If not mine then align to left 
    else { 
     layout.setBackgroundResource(R.drawable.chat_bubble_left); 
     parent_layout.setGravity(Gravity.LEFT); 
    } 
    if (message.isMine) { 
     msg.setTextColor(Color.WHITE); 
    } 

    else { 
     msg.setTextColor(Color.BLACK); 
    } 

    return vi; 
} 

public void add(ChatMessage object) { 
    chatMessageList.add(object); 
} 
}

EmojiMessage.java

package com.bk.cryptit; 

import android.widget.ImageView; 

import java.util.Random; 

public class EmojiMessage { 
public String sender, receiver, senderName; 
public ImageView body; 
public String Date, Time; 
public String msgid; 
public boolean isMine;// Did I send the message. 

public EmojiMessage(String Sender, String Receiver, ImageView emoji, 
        String ID, boolean isMINE) { 
    body = emoji; 
    isMine = isMINE; 
    sender = Sender; 
    msgid = ID; 
    receiver = Receiver; 
    senderName = sender; 
} 
public void setMsgID() { 

    msgid += "-" + String.format("%02d", new Random().nextInt(100)); 
    ; 
} 
}

EmojiAdapter.java

package com.bk.cryptit; 

import java.util.ArrayList; 

import android.app.Activity; 
import android.content.Context; 
import android.graphics.Color; 
import android.text.InputFilter; 
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.LinearLayout; 
import android.widget.TextView; 

public class EmojiAdapter extends BaseAdapter{ 
private static LayoutInflater inflater = null; 
ArrayList<EmojiMessage> chatMessageListEmoji; 

public EmojiAdapter(Activity activity, ArrayList<EmojiMessage> list) { 
    chatMessageListEmoji = list; 
    inflater = (LayoutInflater) activity 
      .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 

} 

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

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

@Override 
public long getItemId(int position) { 
    return position; 
} 

@Override 
public View getView(int position, View convertView, ViewGroup parent) { 
    EmojiMessage message = (EmojiMessage) chatMessageListEmoji.get(position); 
    View vi = convertView; 
    if (convertView == null) 
     vi = inflater.inflate(R.layout.imagechatbubble, null); 

    ImageView msgEmoji = (ImageView) vi.findViewById(R.id.message_image); 
    LinearLayout layout = (LinearLayout) vi 
      .findViewById(R.id.bubble_layout); 
    LinearLayout parent_layout = (LinearLayout) vi 
      .findViewById(R.id.bubble_layout_parent); 

    // if message is mine then align to right 
    if (message.isMine) { 
     parent_layout.setGravity(Gravity.RIGHT); 
    } 
    // If not mine then align to left 
    else { 
     parent_layout.setGravity(Gravity.LEFT); 
    } 

    return vi; 
} 

public void add(EmojiMessage object) { 
    chatMessageListEmoji.add(object); 
} 
}

Chats.java

package com.bk.cryptit; 

import java.util.ArrayList; 
import java.util.Random; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentActivity; 
import android.support.v7.app.ActionBarActivity; 
import android.support.v7.app.AppCompatActivity; 
import android.text.Editable; 
import android.text.TextWatcher; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.view.ViewGroup; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.ImageButton; 
import android.widget.ImageView; 
import android.widget.ListView; 

import com.bk.cryptit.ChatAdapter; 
import com.bk.cryptit.ChatMessage; 
import com.bk.cryptit.CommonMethods; 
import com.bk.cryptit.EmojiMessage; 
import com.bk.cryptit.EmojiAdapter; 
import com.bk.cryptit.R; 

public class Chats extends Fragment { 

private EditText msg_edittext; 
private String user1 = "khushi", user2 = "khushi1"; 
private Random random; 
public static ArrayList<ChatMessage> chatlist; 
public static ArrayList<EmojiMessage> emojilist; 
public static EmojiAdapter emojiAdapter; 
public static ChatAdapter chatAdapter; 
ListView msgListView; 
String editText; 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    View view = inflater.inflate(R.layout.activity_welcome, container, false); 
    random = new Random(); 
    msg_edittext = (EditText) view.findViewById(R.id.editText); 
    msgListView = (ListView) view.findViewById(R.id.messegesListView); 
    editText = msg_edittext.getText().toString(); 
    final ImageButton sendButton = (ImageButton) view 
      .findViewById(R.id.button10); 
    sendButton.setImageResource(R.drawable.like); 
    // ----Set autoscroll of listview when a new message arrives----// 
    msgListView.setTranscriptMode(ListView.TRANSCRIPT_MODE_ALWAYS_SCROLL); 
    msgListView.setStackFromBottom(true); 

    chatlist = new ArrayList<ChatMessage>(); 
    chatAdapter = new ChatAdapter(getActivity(), chatlist); 
    emojilist = new ArrayList<EmojiMessage>(); 
    emojiAdapter = new EmojiAdapter(getActivity(), emojilist); 

    msg_edittext.addTextChangedListener(new TextWatcher() { 
     @Override 
     public void beforeTextChanged(CharSequence s, int start, int count, int after) { 
      if (msg_edittext.getText().length()>0) { 
       sendButton.setImageResource(R.drawable.sending_black); 
       msgListView.setAdapter(chatAdapter); 
      } else sendButton.setImageResource(R.drawable.like); msgListView.setAdapter(emojiAdapter); 
     } 

     @Override 
     public void onTextChanged(CharSequence s, int start, int before, int count) { 
      if (msg_edittext.getText().length()>0) { 
       sendButton.setImageResource(R.drawable.sending_black); 
       msgListView.setAdapter(chatAdapter); 
      } else sendButton.setImageResource(R.drawable.like); msgListView.setAdapter(emojiAdapter); 
     } 

     @Override 
     public void afterTextChanged(Editable s) { 
      if (msg_edittext.getText().length()>0) { 
       sendButton.setImageResource(R.drawable.sending_black); 
       msgListView.setAdapter(chatAdapter); 
      } else sendButton.setImageResource(R.drawable.like); msgListView.setAdapter(emojiAdapter); 
     } 
    }); 
    sendButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      sendTextMessage(v); 
     } 
    }); 




    return view; 
} 

@Override 
public void onSaveInstanceState(Bundle outState) { 
} 

public void sendTextMessage(View v) { 
    String message = msg_edittext.getEditableText().toString(); 
    if (!message.equalsIgnoreCase("")) { 
     final ChatMessage chatMessage = new ChatMessage(user1, user2, 
       message, "" + random.nextInt(1000), true); 
     chatMessage.setMsgID(); 
     chatMessage.body = message; 
     chatMessage.Date = CommonMethods.getCurrentDate(); 
     chatMessage.Time = CommonMethods.getCurrentTime(); 
     msg_edittext.setText(""); 
     chatAdapter.add(chatMessage); 
     chatAdapter.notifyDataSetChanged(); 
    } 
} 
public void sendEmojiMessage(View v) { 
    String message = msg_edittext.getEditableText().toString(); 
    android.support.v7.widget.AppCompatImageView emoji = (android.support.v7.widget.AppCompatImageView) getView().findViewById(R.id.message_image); 
    emoji.setImageResource(R.drawable.like); 
    if (message.equalsIgnoreCase("")) { 
     final EmojiMessage emojiMessage = new EmojiMessage(user1, user2, emoji, "" + random.nextInt(1000), true); 
     emojiMessage.body = emoji; 
     emojiMessage.Date = CommonMethods.getCurrentDate(); 
     emojiMessage.Time = CommonMethods.getCurrentTime(); 
     msg_edittext.setText(""); 
     emojiAdapter.add(emojiMessage); 
     emojiAdapter.notifyDataSetChanged(); 
    } 
} 
}

chatbubble.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:app="http://schemas.android.com/apk/res-auto" 
android:id="@+id/imagebubble_layout_parent" 
android:layout_width="match_parent" 
android:layout_height="match_parent"> 

<LinearLayout 
    android:id="@+id/imagebubble_layout" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_marginRight="24dp" 
    android:layout_marginLeft="56dp" 
    android:background="@android:color/transparent"> 

    <android.support.v7.widget.AppCompatImageButton 
     android:id="@+id/message_image" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_gravity="center" 
     android:background="@android:color/transparent" 
     app:srcCompat="@drawable/like"/> 

</LinearLayout>

imagechatbubble.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:app="http://schemas.android.com/apk/res-auto" 
android:id="@+id/imagebubble_layout_parent" 
android:layout_width="match_parent" 
android:layout_height="match_parent"> 

<LinearLayout 
    android:id="@+id/imagebubble_layout" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_marginRight="24dp" 
    android:layout_marginLeft="56dp" 
    android:background="@android:color/transparent"> 

    <android.support.v7.widget.AppCompatImageButton 
     android:id="@+id/message_image" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_gravity="center" 
     android:background="@android:color/transparent" 
     app:srcCompat="@drawable/like"/> 

</LinearLayout>

来源

2017-07-17 Bartosz Królak

你知道什么是NullPointerException吗？在com.bk.cryptit.Chats.sendEmojiMessage（Chats.java:115） at com.bk.cryptit.Chats $ 2.onClick（Chats.java:77） - >这些是你的错误发生的地方。你正在返回的东西是null – DroiDev

是115行吗？（android.support.v7.widget.AppCompatImageView）getView（）。findViewById（R.id.message_image）;为什么这不是一个ImageView，但你有一个android.support.v7.widget .....等 – DroiDev

因为要显示在棒棒糖android的矢量图像我需要使用AppCompat。 –

首先，我们需要测试的表情符号很容易发送到ListView控件具有它上面的文字。您可以将接口添加到从适配器调用的活动中。该接口将调用最终显示发送按钮或表情符号的TextChangedListener。

来源

2017-07-17 14:33:56

将图像（表情符号）放在ListView上

回答

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