[Java] Room

build.gradle (Module: app)

dependencies {
    // RecyclerView
    implementation 'androidx.recyclerview:recyclerview:1.1.0'

    // Room
    implementation 'androidx.room:room-runtime:2.2.5'
    annotationProcessor 'androidx.room:room-compiler:2.2.5'
    testImplementation 'androidx.room:room-testing:2.2.5'
}

 

 

 

 

 

 

 

 

 

User.java

package com.jwsoft.javaproject;

import androidx.room.ColumnInfo;
import androidx.room.Entity;
import androidx.room.PrimaryKey;

@Entity(tableName = "user")
public class User {

    @PrimaryKey(autoGenerate = true)
    public Long id;

    @ColumnInfo(name = "name")
    public String name;

    @ColumnInfo(name = "phone")
    public String phone;

    @ColumnInfo(name = "age")
    public int age;

}

 

 

 

 

 

 

 

 

UserDao.java

package com.jwsoft.javaproject;

import androidx.room.Dao;
import androidx.room.Delete;
import androidx.room.Insert;
import androidx.room.OnConflictStrategy;
import androidx.room.Query;

import java.util.List;

@Dao
public interface UserDao {

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void insert(User user);

    @Query("SELECT * FROM user ORDER BY id ASC")
    List<User> getAll();

    @Query("DELETE FROM user")
    void deleteAll();

    @Delete
    void delete(User user);

}

 

 

 

 

 

 

 

 

UserDB.java

package com.jwsoft.javaproject;

import android.content.Context;

import androidx.room.Database;
import androidx.room.Room;
import androidx.room.RoomDatabase;

@Database(entities = {User.class}, version = 1)
public abstract class UserDB extends RoomDatabase {

    public abstract UserDao userDao();

    public static UserDB INSTANCE;

    public static UserDB getInstance(Context context) {
        if (INSTANCE == null) {
            INSTANCE = Room.databaseBuilder(context, UserDB.class, "MyApp.db")
                    .fallbackToDestructiveMigration()
                    .build();
        }
        return INSTANCE;
    }

}

 

 

 

 

 

 

 

 

 

recyclerview_item.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="80dp"
    android:layout_margin="8dp">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#FFBBBB"/>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:gravity="center"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintRight_toLeftOf="@+id/tvAge">

        <TextView
            android:id="@+id/tvName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="32dp"
            android:textStyle="bold"
            android:hint="James Kim" />

        <TextView
            android:id="@+id/tvPhone"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:hint="010-1234-5678"
            android:textSize="18dp"
            android:textStyle="italic|bold"
            android:inputType="phone"/>

    </LinearLayout>

    <TextView
        android:id="@+id/tvAge"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:layout_marginRight="10dp"
        android:hint="30"
        android:textSize="40dp"
        android:gravity="center"
        android:textStyle="bold"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

recyclerview_item.xml

 

 

 

 

 

 

 

RecyclerViewAdapter.java

package com.jwsoft.javaproject;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder> {
    List<User> mData;

    public RecyclerViewAdapter(List<User> data) {
        mData = data;
    }

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView tvName;
        TextView tvPhone;
        TextView tvAge;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            tvName = itemView.findViewById(R.id.tvName);
            tvPhone = itemView.findViewById(R.id.tvPhone);
            tvAge = itemView.findViewById(R.id.tvAge);
        }

        void bind(User user) {
            tvName.setText(user.name);
            tvPhone.setText(user.phone);
            tvAge.setText(Integer.toString(user.age));
        }
    }

    @NonNull
    @Override
    public RecyclerViewAdapter.MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        Context context = parent.getContext();
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View view = inflater.inflate(R.layout.recyclerview_item, parent, false);

        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerViewAdapter.MyViewHolder holder, int position) {
        holder.bind(mData.get(position));
    }

    @Override
    public int getItemCount() {
        return mData.size();
    }
}

 

 

 

 

 

 

 

 

activity_add.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".AddActivity">


    <TextView
        android:id="@+id/tvName"
        android:text="Name"
        android:textSize="18dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="32dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintVertical_bias="0.41000003"/>

    <EditText
        android:id="@+id/etName"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:ems="10"
        app:layout_constraintBottom_toBottomOf="@+id/tvName"
        app:layout_constraintTop_toTopOf="@+id/tvName"
        app:layout_constraintStart_toEndOf="@+id/tvName"
        android:layout_marginStart="32dp"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginEnd="32dp"/>

    <TextView
        android:id="@+id/tvPhone"
        android:text="Number"
        android:textSize="18dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="40dp"
        app:layout_constraintTop_toBottomOf="@+id/tvName"
        app:layout_constraintStart_toStartOf="@+id/tvName"/>

    <EditText
        android:id="@+id/etPhone"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:ems="10"
        app:layout_constraintStart_toStartOf="@+id/etName"
        app:layout_constraintTop_toTopOf="@+id/tvPhone"
        app:layout_constraintBottom_toBottomOf="@+id/tvPhone"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginEnd="32dp"
        android:inputType="phone"/>

    <TextView
        android:id="@+id/tvAge"
        android:text="Age"
        android:textSize="18dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="40dp"
        app:layout_constraintTop_toBottomOf="@+id/tvPhone"
        app:layout_constraintStart_toStartOf="@+id/tvPhone"/>

    <EditText
        android:id="@+id/etAge"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:ems="10"
        app:layout_constraintStart_toStartOf="@+id/etPhone"
        app:layout_constraintTop_toTopOf="@+id/tvAge"
        app:layout_constraintBottom_toBottomOf="@+id/tvAge"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginEnd="32dp"
        android:inputType="phone"/>

    <Button
        android:id="@+id/btnAdd"
        android:text="Add"
        android:layout_width="0dp"
        android:layout_height="49dp"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginStart="8dp"
        android:layout_marginEnd="8dp"/>

</androidx.constraintlayout.widget.ConstraintLayout>

activity_add.xml

 

 

 

 

 

 

AddAcitivity.java

package com.jwsoft.javaproject;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class AddActivity extends AppCompatActivity {

    EditText etName;
    EditText etPhone;
    EditText etAge;
    Button btnAdd;

    Intent intent;

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

        initializeView();
        intent = new Intent(this, MainActivity.class);

        btnAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        User user = new User();
                        user.name = etName.getText().toString();
                        user.phone = etPhone.getText().toString();
                        user.age = Integer.parseInt(etAge.getText().toString());

                        UserDB.getInstance(getApplicationContext()).userDao().insert(user);
                        startActivity(intent);
                        finish();
                    }
                }).start();

            }
        });

    }

    void initializeView() {
        etName = findViewById(R.id.etName);
        etPhone = findViewById(R.id.etPhone);
        etAge = findViewById(R.id.etAge);
        btnAdd = findViewById(R.id.btnAdd);
    }

}

 

 

 

 

 

 

 

 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        tools:listitem="@layout/recyclerview_item"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toTopOf="@+id/btnAdd"/>

    <Button
        android:id="@+id/btnAdd"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="add"
        android:textSize="24dp"
        app:layout_constraintTop_toBottomOf="@+id/recyclerView"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

activity_main.xml

 

 

 

 

 

 

MainActivity.java

package com.jwsoft.javaproject;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import java.util.List;

public class MainActivity extends AppCompatActivity {

    Button btnAdd;
    RecyclerView recyclerView;
    Intent intent;
    List<User> users;

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

        initializeView();
        intent = new Intent(this, AddActivity.class);

        btnAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(intent);
                finish();
            }
        });


        new Thread(new Runnable() {
            @Override
            public void run() {
                users = UserDB.getInstance(getApplicationContext()).userDao().getAll();
                RecyclerViewAdapter adapter = new RecyclerViewAdapter(users);
                recyclerView.setAdapter(adapter);
                recyclerView.setLayoutManager(new LinearLayoutManager(
                        getApplicationContext(),
                        RecyclerView.VERTICAL,
                        false)
                );
            }
        }).start();

    }

    void initializeView() {
        btnAdd = findViewById(R.id.btnAdd);
        recyclerView = findViewById(R.id.recyclerView);
    }

}

실행 결과

 

 

ADD 버튼 클릭 후 화면

 

정보 입력 후 버튼 클릭

 

추가 완료

 

앱 종료 후 재실행