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在选项卡式活动中将sqlite数据库中的所有数据显示到listview中

android-fragmentactivity listview sqlite android

major · 技术社区 · 7 年前

作为android开发的新手,我已经在这个问题上纠结了几个星期了,现在已经很累了。

在阅读了每一篇教程并阅读了我能找到的每一个问题和答案之后,我仍然不知道如何让Android Studio只获取我的SQLite数据库中的内容并将其内容粘贴到 listview . 我本以为会有 android:displayallfrom("myDB") 在XML文件中执行某种命令,只显示数据库中的所有内容,但看起来要复杂得多。

基本上,我想做的是 显示我的数据库中的所有数据 ( Dogs.db )进入我的 列表视图 ( list_dogs )在我的选项卡视图的第一个选项卡中( Tab1 ).

这是我的代码:

Tab1.java

package com.example.major.awoo;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class Tab1 extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.tab1, container, false);
        return rootView;
    }
}

tab1.xml

<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: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="com.example.major.awoo.MainActivity">

    <ListView
        android:id="@+id/list_dogs"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:listSelector=""/>

</RelativeLayout>

DatabaseHelper。Java语言

package com.example.major.awoo;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseHelper extends SQLiteOpenHelper {
    public static final String DATABASE_NAME = "Dogs.db";
    public static final String TABLE_NAME = "dogs_table";
    public static final String COL_1 = "ID";
    public static final String COL_2 = "NAME";
    public static final String COL_3 = "AGE";
    public static final String COL_4 = "WEIGHT";
    public static final String COL_5 = "BREED";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
            db.execSQL("create table " + TABLE_NAME +" (ID INTEGER PRIMARY KEY AUTOINCREMENT,NAME TEXT,SURNAME TEXT,MARKS INTEGER)");
    }


    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);
        onCreate(db);
    }

    public boolean insertData(String name,String age,String weight,String breed) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(COL_2,name);
        contentValues.put(COL_3,age);
        contentValues.put(COL_4,weight);
        contentValues.put(COL_5,breed);
        long result = db.insert(TABLE_NAME, null, contentValues);
        if(result == -1)
            return false;
        else
            return true;
    }

    public Cursor getAllData() {
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor res = db.rawQuery("select * from "+TABLE_NAME,null);
        return res;
    }

    public boolean updateData(String id,String name,String age,String weight,String breed) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(COL_1,id);
        contentValues.put(COL_2,name);
        contentValues.put(COL_3,age);
        contentValues.put(COL_4,weight);
        contentValues.put(COL_5,breed);
        db.update(TABLE_NAME, contentValues, "ID = ?",new String[] { id });
        return true;
    }

    public Integer deleteData (String id) {
        SQLiteDatabase db = this.getWritableDatabase();
        return db.delete(TABLE_NAME, "ID = ?",new String[] {id});

    }

    public Cursor getListContents(){
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor data = db.rawQuery("SELECT * FROM " + TABLE_NAME,null);
        return data;
}

//method to display data

    public Cursor displayData;
    {
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor res = db.rawQuery(" SELECT  * FROM " + TABLE_NAME, null);
        return res;    
    }   

}

我确信我错过了一些非常愚蠢的事情,但如果有任何帮助,我将不胜感激。

1 回复 | 直到 7 年前

Yousaf 6 年前

如果你想显示每个人的每一个信息 dog 在一个 ListView ,您需要 Dog 班虽然这不是必需的,但它会使您的工作更轻松,而且从数据库中获取数据并存储每个 狗 在一个 狗 类实例。

public class Dog {
    private String id;
    private String name;
    private String age;
    private String breed;
    private String weight;

    public Dog(String id, String name, String age, String breed, String weight) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.breed = breed;
        this.weight = weight;
    }

    public String getID() {
        return this.id;
    }

    public String getName() {
        return this.name;
    }

    public String getAge() {
        return this.age;
    }

    public String getWeight() {
        return this.weight;
    }

    public String getBreed() {
        return this.breed;
    }
}

然后需要定义 layout XML 将表示 列表视图 . 您可以按照自己的方式进行设计。

这是一个实例行布局代码

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <TextView
        android:id="@+id/text_dogID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="demo"
        android:textColor="#000"
        android:textSize="25sp"/>

    <TextView
        android:id="@+id/text_dogName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="demo"
        android:textColor="#000"
        android:textSize="25sp"
        app:layout_constraintTop_toBottomOf="@id/text_dogID"/>

    <TextView
        android:id="@+id/text_dogAge"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="demo"
        android:textColor="#000"
        android:textSize="25sp"
        app:layout_constraintTop_toBottomOf="@id/text_dogName"/>

    <TextView
        android:id="@+id/text_dogWeight"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="demo"
        android:textColor="#000"
        android:textSize="25sp"
        app:layout_constraintTop_toBottomOf="@id/text_dogAge"/>

    <TextView
        android:id="@+id/text_dogBreed"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="demo"
        android:textColor="#000"
        android:textSize="25sp"
        app:layout_constraintTop_toBottomOf="@id/text_dogWeight"/>

</android.support.constraint.ConstraintLayout>

之后,你需要自己的 custom adapter 将其分类 extends 这个 BaseAdapter 类别和 Override 这个 getView 方法

这是一个实例自定义适配器类

public class CustomAdapter extends BaseAdapter{

    private ArrayList<Dog> dogsList;
    private Context context;

    public CustomAdapter(ArrayList<Dog> list, Context cont){
        this.dogsList = list;
        this.context = cont;
    }

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

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;

        if(convertView == null){
            LayoutInflater inf = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inf.inflate(R.layout.listview_row_layout, null);

            holder = new ViewHolder();
            holder.id = (TextView)convertView.findViewById(R.id.text_dogID);
            holder.name = (TextView)convertView.findViewById(R.id.text_dogName);
            holder.age = (TextView)convertView.findViewById(R.id.text_dogAge);
            holder.weight = (TextView)convertView.findViewById(R.id.text_dogWeight);
            holder.breed = (TextView)convertView.findViewById(R.id.text_dogBreed);

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

        Dog stu = dogsList.get(position);
        holder.id.setText(stu.getID());
        holder.name.setText(stu.getName());
        holder.age.setText(stu.getAge());
        holder.weight.setText(stu.getWeight());
        holder.breed.setText(stu.getBreed());

        return convertView;
    }

    private static class ViewHolder{
        public TextView id;
        public TextView name;
        public TextView age;
        public TextView weight;
        public TextView breed;
    }
}

现在,您需要从数据库中获取数据,并将每只狗的信息存储在单独的 狗 前面创建的类实例。

public ArrayList<Dog> getAllData() {
        ArrayList<Dog> doglist = new ArrayList<>();
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor res = db.rawQuery("select * from "+TABLE_NAME,null);

        while(res.moveToNext()) {
            String id = res.getString(0);   //0 is the number of id column in your database table
            String name = res.getString(1);
            String age = res.getString(2);
            String breed = res.getString(3);
            String weight = res.getString(4);

            Dog newDog = new Dog(id, name, age, breed, weight);
            doglist.add(newDog);
        }
        return doglist;
 }

现在,数据库中的所有数据都存储在 狗 存储在中的类 doglist ArrayList .

最后,您需要一种方法来填充 列表视图

public void fillListview() {
     ListView myListview = findViewById(R.id.myListview);
     DatabaseHelper dbhelper = new DatabaseHelper(this);

     ArrayList<Dog> dogList = dbhelper.getAllData();

     Customadapter myAdapter = new Customadapter(dogList, this);
     myListview.setAdapter(myAdapter);
}