Question

我的代码如下。当用户在EditText上键入时，我想过滤列表视图的数据。我的数据源是一个数据库。它给出了空指针异常！

请有人帮助我。

我的代码如下。当用户在EditText上键入时，我想过滤列表视图的数据。我的数据源是一个数据库。它给出了空指针异常！

请有人帮助我。

 package com.learn24bd.dictionary;

    import java.util.ArrayList;
    import android.app.Activity;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.os.Bundle;
    import android.text.Editable;
    import android.text.TextWatcher;
    import android.widget.ArrayAdapter;
    import android.widget.EditText;
    import android.widget.ListView;

    public class MainActivity extends Activity {
        private SQLiteDatabase database;
        private static final String DB_NAME = "myDictionary";
        private static final String TABLE_NAME = "sortForm";
        private static final String SORT_FORM = "field2";
        private static final String FULL_FORM = "field3";
        EditText etSearch;
        public ArrayList<String> friends;
        ArrayAdapter<String> adapter1;

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

            etSearch = (EditText) findViewById(R.id.etSearch);
            ListView lvFirst = (ListView) findViewById(R.id.lvFirst);
            // at this on create method for open the database
            ExternalDbOpenHelper dbOpenHelper = new ExternalDbOpenHelper(this,
                    DB_NAME);
            database = dbOpenHelper.openDataBase();

            lvFirst.setTextFilterEnabled(true);

            adapter1 = new ArrayAdapter<String>(MainActivity.this,
                    android.R.layout.simple_list_item_1, friends);
            lvFirst.setAdapter(adapter1);

            etSearch.addTextChangedListener(new TextWatcher() {

                @Override
                public void onTextChanged(CharSequence arg0, int arg1, int arg2,
                        int arg3) {
                    // TODO Auto-generated method stub
                    MainActivity.this.adapter1.getFilter().filter(arg0);
                }
                @Override
                public void beforeTextChanged(CharSequence arg0, int arg1,
                        int arg2, int arg3) {

                }
                @Override
                public void afterTextChanged(Editable arg0) {

                }
            });

            friends = new ArrayList<String>();
            Cursor friendCursor = database.query(TABLE_NAME, new String[] {
                    SORT_FORM, FULL_FORM }, null, null, null, null, FULL_FORM);
            friendCursor.moveToFirst();
            if (!friendCursor.isAfterLast()) {
                do {
                    String sForm = friendCursor.getString(0);
                    String fForm = friendCursor.getString(1);
                    friends.add(sForm);
                    friends.add(fForm);
                } while (friendCursor.moveToNext());
            }
            friendCursor.close();
        }
    }

我的XML文件是

<?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:orientation="vertical" >

    <EditText
        android:id="@+id/etSearch"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" >
        <requestFocus />
    </EditText>
    <ListView
        android:id="@+id/lvFirst"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" >
    </ListView>

</LinearLayout>

请帮助

Answer 1

您需要更改您的pojo类toString方法或类似于给定链接中的处理

Custom filtering in Android using ArrayAdapter

通过EditText从数据库中过滤ListView

1 个答案: