Android中在ListView的Adapter实现启动Activity和改变Activity属性

微信界面里面的联系人中，我们点击其中任意的Item就会出现不同的Activity。

这个需求的实现是在listView中的Adapter中实现的，在点击的事件被监听之后触发Intent携带一个值去启动一个新的Activity，携带的值决定了新的Activity的形态和属性。

总的来说，是Intent传值问题。

具体代码如下：

1、Adapter的java代码：

package com.example.app_weixin;import android.content.Context;import android.content.Intent;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.RelativeLayout;import android.widget.TextView;import java.util.List;import java.util.Map;/** * Created by 尽途 on 2017/3/27. */public class contactAdapter extends BaseAdapter {    private List<Map<String,Object>>contactdata;    private LayoutInflater minflater;    private Context context;    public contactAdapter(Context context,List<Map<String,Object>>list){        this.context=context;        this.minflater=LayoutInflater.from(context);        this.contactdata=list;    }    public final class ViewHoder{        public TextView userNameTextview;        public ImageView userImageview;        public RelativeLayout itemlayout;    }    @Override    public Object getItem(int position) {        return null;    }    @Override    public long getItemId(int position) {        return 0;    }    @Override    public int getCount() {        return contactdata.size();    }    @Override    public View getView(final int position, View convertView, ViewGroup parent) {        ViewHoder hoder=null;        if (convertView==null){            hoder=new ViewHoder();            convertView=minflater.inflate(R.layout.item_contact,null);            hoder.userNameTextview=(TextView)convertView.findViewById(R.id.username_contact);            hoder.userImageview=(ImageView)convertView.findViewById(R.id.userImage_iv_contact);            hoder.itemlayout=(RelativeLayout)convertView.findViewById(R.id.item_contact);            convertView.setTag(hoder);        }else {            hoder=(ViewHoder)convertView.getTag();        }        hoder.userNameTextview.setText((String)contactdata.get(position).get("username"));        hoder.userImageview.setImageResource((Integer)contactdata.get(position).get("userimage"));        hoder.itemlayout.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                /**                 * 决定了新Activity的形态属性                 */                String strname=(String)contactdata.get(position).get("username");                switch (strname){                    case "新的朋友":                        Intent mintent=new Intent(context,Activity_addfriend.class);                        mintent.putExtra("name",strname);                        context.startActivity(mintent);                        break;                    case "群聊":                        Intent qintent=new Intent(context,Activity_qunliao.class);                        qintent.putExtra("name",strname);                        context.startActivity(qintent);                        break;                    case "标签":                        Intent lintent=new Intent(context,Activity_label.class);                        lintent.putExtra("name",strname);                        context.startActivity(lintent);                        break;                    case "公众号":                        Intent pintent=new Intent(context,Activity_public.class);                        pintent.putExtra("name",strname);                        context.startActivity(pintent);                        break;                    default:                        Intent cintent=new Intent(context,Activity_contact.class);                        cintent.putExtra("name",strname);                        context.startActivity(cintent);                        break;                }            }        });        return convertView;    }}

2、Adapter的Item的Xml代码：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent">    <RelativeLayout        android:id="@+id/item_contact"        android:clickable="true"        android:background="@drawable/find_background"        android:layout_width="fill_parent"        android:layout_height="55dp">        <ImageView            android:id="@+id/userImage_iv_contact"            android:scaleType="centerInside"            android:padding="8dp"            android:layout_width="50dip"            android:layout_height="wrap_content"            android:src="@drawable/icon_addfriend"            android:layout_marginStart="5dp"            android:layout_centerVertical="true"            android:layout_alignParentStart="true"/>        <LinearLayout            android:padding="5dp"            android:layout_width="match_parent"            android:layout_height="match_parent"            android:orientation="vertical"            android:layout_toEndOf="@+id/userImage_iv_contact">            <TextView                android:id="@+id/username_contact"                android:padding="10dp"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="用户名"                android:textColor="@color/colorBlack"                android:layout_gravity="center_vertical"                android:textSize="15sp"/>        </LinearLayout>    </RelativeLayout></LinearLayout>

3、chatActivity的java代码

package com.example.app_weixin;import android.content.Intent;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.EditText;import android.widget.ImageView;import android.widget.ListView;import android.widget.TextView;public class ChatActivity extends AppCompatActivity {    private ImageView backImageview;    private EditText editTextmessage;    private TextView textSendmessage;    private TextView nameTextview;    private ListView messageListview;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_chat);        Intent mintent=getIntent();        String name=mintent.getStringExtra("username");        nameTextview.setText(name);    }}

4、chatActivity中的xml代码

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:background="@color/colorLineBold"    android:orientation="vertical">    <FrameLayout        android:layout_width="match_parent"        android:layout_height="wrap_content">        <LinearLayout            android:id="@+id/titleBar"            android:layout_width="match_parent"            android:background="@color/colorbackground"            android:layout_height="48dp"            android:orientation="horizontal">            <ImageView                android:padding="15dp"                android:id="@+id/back_iv"                android:clickable="true"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:layout_gravity="center"                android:onClick="omBackground"                android:src="@drawable/icon_back"                android:background="@drawable/normalorpressed_background"                android:visibility="visible"/>            <TextView                android:id="@+id/name_tv"                android:layout_gravity="bottom"                android:padding="10dp"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="用户名"                android:textSize="18sp"                android:textColor="#ffff" />        </LinearLayout>    </FrameLayout>    <ListView        android:layout_weight="1"        android:id="@+id/message_list"        android:divider="@null"        android:layout_width="match_parent"        android:layout_height="match_parent">    </ListView>    <LinearLayout        android:background="#ffff"        android:layout_width="match_parent"        android:layout_height="45dp"        android:orientation="horizontal">        <EditText            android:id="@+id/edit_message"            android:layout_weight="1"            android:textColor="@color/colorBlack"            android:layout_width="match_parent"            android:layout_height="match_parent" />        <TextView            android:id="@+id/sendmessage"            android:clickable="true"            android:layout_gravity="center"            android:padding="12dp"            android:textSize="15sp"            android:background="@drawable/green_background"            android:text="发送"            android:layout_width="wrap_content"            android:layout_height="wrap_content" />    </LinearLayout></LinearLayout>