将 sqlite 数据库中的所有数据显示到选项卡中的列表视图中 activity
Displaying ALL data from sqlite database into listview in tabbed activity
作为 android 开发的新手，我已经在这个问题上停留了几个星期了，它变得非常累人。
在查看了每个教程并阅读了我能找到的每个问题和答案之后，我仍然无法弄清楚如何让 Android Studio 只获取我的 SQLite 数据库中的内容并将其内容粘贴到listview。我原以为 XML 文件中会有某种 android:displayallfrom("myDB") 命令来显示数据库中的所有内容，但它似乎要复杂得多。
基本上，我想做的是显示我数据库中的所有数据 (Dogs.db) 到我的 listview (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
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;
}
}
我确定我遗漏了一些非常愚蠢的东西，但我们将不胜感激。
如果要在ListView中显示每个dog的每一个信息，则需要制作Dogclass。虽然这不是必需的，但它会使您的工作更轻松，并且从数据库中获取数据并将每个 dog 的信息存储在 Dog class 实例中会更有意义。
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;
}
}
然后您需要定义一个 layout XML 文件来表示 ListView 的每一行。你可以随心所欲地设计它。
这是一个示例行布局代码
<?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>
在此之后，你需要自己的custom adapter class extends BaseAdapter class Override getView ]方法。
这是一个 示例 自定义适配器 class
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您之前创建的单独 Dog class 实例中。
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;
}
现在您数据库中的所有数据都存储在 Dog class 的实例中，这些实例存储在 doglist ArrayList 中。
最后你需要一个方法来填充你的 ListView
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);
}
作为 android 开发的新手，我已经在这个问题上停留了几个星期了，它变得非常累人。
在查看了每个教程并阅读了我能找到的每个问题和答案之后，我仍然无法弄清楚如何让 Android Studio 只获取我的 SQLite 数据库中的内容并将其内容粘贴到listview。我原以为 XML 文件中会有某种 android:displayallfrom("myDB") 命令来显示数据库中的所有内容，但它似乎要复杂得多。
基本上，我想做的是显示我数据库中的所有数据 (Dogs.db) 到我的 listview (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
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;
}
}
我确定我遗漏了一些非常愚蠢的东西，但我们将不胜感激。
如果要在ListView中显示每个dog的每一个信息，则需要制作Dogclass。虽然这不是必需的，但它会使您的工作更轻松，并且从数据库中获取数据并将每个 dog 的信息存储在 Dog class 实例中会更有意义。
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;
}
}
然后您需要定义一个 layout XML 文件来表示 ListView 的每一行。你可以随心所欲地设计它。
这是一个示例行布局代码
<?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>
在此之后，你需要自己的custom adapter class extends BaseAdapter class Override getView ]方法。
这是一个 示例 自定义适配器 class
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您之前创建的单独 Dog class 实例中。
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;
}
现在您数据库中的所有数据都存储在 Dog class 的实例中，这些实例存储在 doglist ArrayList 中。
最后你需要一个方法来填充你的 ListView
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);
}