在Android中创建自定义ListView的问题

时间：2013-08-18 11:42:27

标签： android android-listview

我正在尝试为Android应用程序设计ArrayList的自定义数组适配器。

我需要的是要显示的项目列表，每个项目的位置包含一个复选框和一个描述性文本。我想我需要实现baseAdapter的扩展才能做到这一点。 我无法让它发挥作用。请指出我的错误。

以下是我的主要活动屏幕，只包含一个按钮和一个listView，两者都已经打包在RelativeLayout中。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/background"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".HomeActivity" >

    <Button
        android:id="@+id/addTaskButton"
        android:textSize="30sp"
        style="@style/bottomButton"
        android:text="@string/addTaskButtonText"/>

    <ListView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/addTaskButton"    
        android:id="@+id/list">     
    </ListView>



</RelativeLayout>

以下是上述屏幕的listView中单个项目的布局。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/singleItemContainer" 
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="10dip">
    <CheckBox
        android:id="@+id/taskDoneCheckBox"
        android:layout_alignParentLeft="true">      
    </CheckBox>
    <TextView 
        android:id="@+id/taskDescriptionTextView"
        android:layout_toRightOf="@+id/taskDoneCheckBox"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:padding="10dip"/>
</RelativeLayout>

以下是我创建的自定义适配器。

public class MyListAdapter extends BaseAdapter {

    private Activity activity;
    private ArrayList<HashMap<String, String>> data;
    private static LayoutInflater inflater=null;


    public MyListAdapter(Activity a, ArrayList<HashMap<String, String>> d) {
        activity = a;
        data=d;
        inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    }

    public int getCount() {
        return data.size();
    }

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

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

    public View getView(int position, View convertView, ViewGroup parent) {
        View vi=convertView;
        if(convertView==null)
            vi = inflater.inflate(R.layout.list_item, null);

        CheckBox taskDoneCheckBox = (CheckBox) vi.findViewById(R.id.taskDoneCheckBox);
        TextView taskDescriptionTextView = (TextView)vi.findViewById(R.id.taskDescriptionTextView); 

        HashMap<String, String> task = new HashMap<String, String>();
        task = data.get(position);

        // Setting all values in listview
        if(task.get(HomeActivity.IS_TASK_DONE) == "false")
            taskDoneCheckBox.setChecked(false);
        else
            taskDoneCheckBox.setChecked(true);

        taskDescriptionTextView.setText(task.get(HomeActivity.TASK_DESCRIPTION));
        return vi;
    }
}

最后，以下是mainActivity类。我已经标记了存在会使应用程序崩溃的行。

public class HomeActivity extends Activity {

    public static final String IS_TASK_DONE = "isTaskDone";
    public static final String TASK_DESCRIPTION = "taskDescription";

    MyListAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);

        //setting up font for the "add task" button.
        Typeface tf = Typeface.createFromAsset(getAssets(),"Fonts/doridrobot.ttf");
        Button addTaskButton = (Button) findViewById(R.id.addTaskButton);
        addTaskButton.setTypeface(tf);

        // storing string resources into HashMap
        ArrayList<HashMap<String,String>> taskList = new ArrayList<HashMap<String,String>>();

        HashMap<String,String> task = new HashMap<String,String>();
        task.put(IS_TASK_DONE, "false");
        task.put(TASK_DESCRIPTION, "Let this be task 1");
        taskList.add(task);

        HashMap<String,String> task1 = new HashMap<String,String>();
        task1.put(IS_TASK_DONE, "true");
        task1.put(TASK_DESCRIPTION, "Let this be task 2");
        taskList.add(task1);


        ListView itemList = (ListView) findViewById(R.id.list);
        adapter = new MyListAdapter(this,taskList);
        itemList.setAdapter(adapter);   //<----- THIS IS THE ONE

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.home, menu);
        return true;
    }

}

删除OnCreate函数中的最后一行“有助于”应用程序不会崩溃，但随后列表仍为空...我该如何解决此问题？

3 个答案:

答案 0 :(得分：0)

请发布您的logcat输出以了解您到底发生了什么事故，虽然我现在可以指出的错误是，

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

这里你需要把

 public Object getItem(int position) {
    return data.get(position);
}

答案 1 :(得分：0)

发布您的日志cat错误可能是b＆＃39;因为您没有指定任何布局宽度和高度属性 android：layout_width =＆＃34; wrap_content＆＃34;机器人：layout_height =＆＃34; WRAP_CONTENT＆＃34;

为list_item指定一些宽度和高度：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/singleItemContainer"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="10dip" >

<CheckBox
    android:id="@+id/taskDoneCheckBox"
    android:layout_alignParentLeft="true" 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">
</CheckBox>

<TextView
    android:id="@+id/taskDescriptionTextView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:layout_toRightOf="@+id/taskDoneCheckBox" />

答案 2 :(得分：0)

我已经检查了这个并且它正在运行：

<强> litsitem.xml 

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <CheckBox
        android:id="@+id/taskDoneCheckBox"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="" />

    <TextView
        android:id="@+id/taskDescriptionTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/checkBox1"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:text="Large Text"
        android:textAppearance="?android:attr/textAppearanceLarge" />

</RelativeLayout>

<强> activity_main.xml中 

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <Button
        android:id="@+id/addTaskButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:text="Button" />

    <ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/addTaskButton" >
    </ListView>

</RelativeLayout>

<强> HomeActivity.java 

import java.util.ArrayList;
import android.os.*;
import android.widget.*;
import java.util.HashMap;
import android.app.Activity;

public class HomeActivity extends Activity {

    public static final String IS_TASK_DONE = "isTaskDone";
    public static final String TASK_DESCRIPTION = "taskDescription";

    MyListAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ArrayList<HashMap<String,String>> taskList = new ArrayList<HashMap<String,String>>();

        HashMap<String,String> task = new HashMap<String,String>();
        task.put(IS_TASK_DONE, "false");
        task.put(TASK_DESCRIPTION, "Let this be task 1");
        taskList.add(task);

        HashMap<String,String> task1 = new HashMap<String,String>();
        task1.put(IS_TASK_DONE, "true");
        task1.put(TASK_DESCRIPTION, "Let this be task 2");
        taskList.add(task1);


        ListView itemList = (ListView) findViewById(R.id.list);
        adapter = new MyListAdapter(this, taskList);
        itemList.setAdapter(adapter);

    }
}

<强> MyListAdapter 

import java.util.ArrayList;
import java.util.HashMap;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.TextView;

public class MyListAdapter extends BaseAdapter {

    private Context activity;
    private ArrayList<HashMap<String, String>> data;
    private static LayoutInflater inflater=null;


    public MyListAdapter(Context a, ArrayList<HashMap<String, String>> d) {
        activity = a;
        data=d;
        inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    }

    public int getCount() {
        return data.size();
    }

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

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

    public View getView(int position, View convertView, ViewGroup parent) {
        View vi=convertView;
        if(convertView==null)
            vi = inflater.inflate(R.layout.listitem, null);

        CheckBox taskDoneCheckBox = (CheckBox) vi.findViewById(R.id.taskDoneCheckBox);
        TextView taskDescriptionTextView = (TextView)vi.findViewById(R.id.taskDescriptionTextView); 

        HashMap<String, String> task = new HashMap<String, String>();
        task = data.get(position);

        // Setting all values in listview
        if(task.get(HomeActivity.IS_TASK_DONE) == "false")
            taskDoneCheckBox.setChecked(false);
        else
            taskDoneCheckBox.setChecked(true);

        taskDescriptionTextView.setText(task.get(HomeActivity.TASK_DESCRIPTION));
        return vi;
    }
}
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