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在選項卡式活動中將所有數據從sqlite數據庫顯示到列表視圖中

[英]Displaying ALL data from sqlite database into listview in tabbed activity

作為android開發的新手,我已經在這個問題上停留了幾周了,它變得很累人。

在閱讀完所有教程並閱讀了所有可以找到的問題和答案之后,我仍然無法弄清楚如何使Android Studio僅僅使用SQLite數據庫中的內容並將其內容粘貼到listview 我本以為在XML文件中會有某種android:displayallfrom("myDB")命令來僅顯示數據庫中存在的所有內容,但這似乎要復雜得多。

基本上,我想要做的是顯示從我的數據庫所有數據 Dogs.db )進入我的listviewlist_dogs在我的標簽視圖(第一片) Tab1 )。

這是我的代碼:

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

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;    
    }   

}

我敢肯定我確實缺少一些愚蠢的東西,但是任何幫助將不勝感激。

如果要在ListView顯示每條dog每條信息,則需要創建一個Dog類。 盡管這不是必需的,但它會使您的工作更輕松,並且從數據庫中獲取數據並將每條dog的信息存儲在Dog類實例中將更有意義。

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,您需要定義一個layout XML文件,該文件將代表ListView的每一行。 您可以根據需要設計它。

這是示例行布局代碼

<?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>

此后,您需要自己的custom adapter類,該類可extends BaseAdapter類並Override getView方法。

這是一個示例自定義適配器類

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;
    }
}

現在,您需要從數據庫中獲取數據,並將每只狗的信息存儲在您先前創建的單獨的Dog類實例中。

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;
 }

現在,數據庫中的所有數據都存儲在Dog類的實例中,該實例存儲在doglist ArrayList

最后,您需要一個可以填充ListView的方法

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);
}

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