한글공부 Hangul Study

안드로이드 애드몹 보상형(리워드)광고 implementation 'com.google.android.gms:play-services-ads:20.2.0' 추가하기 출처: https://toytvstory.tistory.com/2180 Cannot fit requested classes in a single dex file (# methods: 66104 65536) 에러 메시지 수정방법 출처: https://toytvstory.tistory.com/2180

https://youtu.be/aPROAyXMzv4

안드로이드 애드몹 전면광고 implementation 'com.google.android.gms:play-services-ads:20.1.0' 를 추가해주세요 출처: https://toytvstory.tistory.com/2179 [뽀로로친구에디] implementation 'com.google.android.gms:play-services-ads:20.2.0'

https://youtu.be/lXhAMetLBf4

Choose Empty Activity.

Enter a project name.

Choose activity_main.xml.

Add a button.

Delete TextView (Hello World) by pressing Delete key

Add android:onClick attribute inside <Button> tag

<?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">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        android:onClick="onButtonClicked"
        tools:layout_editor_absoluteX="158dp"
        tools:layout_editor_absoluteY="316dp"
        tools:ignore="MissingConstraints" />

</androidx.constraintlayout.widget.ConstraintLayout>

Let's make a message appear when a button is pressed.

You need to link the button you added in activity_main.xml to MainActivity.java.

package com.jw.messageexample;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

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

    }

    public void onButtonClicked(View view){
        Toast.makeText(this,"Button clicked",Toast.LENGTH_LONG).show();

    }
}

That way, the click event from the button can be handled in the Java source.

Toast serves as a small, brief display of messages.

Press Alt + Enter to resolve import errors.

Run app

When you press the button, you can see that the message appears and disappears at the bottom of the screen.

안드로이드 SQLite 데이터베이스 CRUD 간단 예제 

긴 말 필요없이 소스코드로

먼저 레이아웃부터 만들겠습니다. 간단히 만들었습니다. 

<?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">

    <EditText
        android:id="@+id/editTextName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="112dp"
        android:layout_marginTop="60dp"
        android:ems="10"
        android:inputType="textPersonName"

        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/editTextPhone"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="112dp"
        android:layout_marginTop="36dp"
        android:ems="10"
        android:inputType="textPersonName"

        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editTextName" />

    <EditText
        android:id="@+id/editTextAddress"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="112dp"
        android:layout_marginTop="16dp"
        android:ems="10"
        android:inputType="textPersonName"

        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editTextPhone" />

    <Button
        android:id="@+id/buttonInsert"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="48dp"
        android:layout_marginTop="48dp"
        android:text="추가하기"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editTextAddress" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="73dp"
        android:layout_marginEnd="38dp"
        android:text="이름"
        app:layout_constraintEnd_toStartOf="@+id/editTextName"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="22dp"
        android:layout_marginTop="71dp"
        android:layout_marginEnd="32dp"
        android:text="전화번호"
        app:layout_constraintEnd_toStartOf="@+id/editTextPhone"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="22dp"
        android:layout_marginTop="32dp"
        android:layout_marginEnd="32dp"
        android:text="주소"
        app:layout_constraintEnd_toStartOf="@+id/editTextAddress"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2" />

    <Button
        android:id="@+id/buttonView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="27dp"
        android:layout_marginTop="46dp"
        android:text="보여주기"
        app:layout_constraintStart_toEndOf="@+id/buttonInsert"
        app:layout_constraintTop_toBottomOf="@+id/editTextAddress" />

    <Button
        android:id="@+id/buttonUpdate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="44dp"
        android:layout_marginTop="11dp"
        android:text="수정하기"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/buttonInsert" />

    <EditText
        android:id="@+id/editTextID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="29dp"
        android:layout_marginTop="15dp"
        android:ems="10"
        android:inputType="textPersonName"

        app:layout_constraintStart_toEndOf="@+id/buttonUpdate"
        app:layout_constraintTop_toBottomOf="@+id/buttonView" />

    <Button
        android:id="@+id/buttonDelete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="42dp"
        android:layout_marginTop="29dp"
        android:text="삭제"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/buttonUpdate" />
</androidx.constraintlayout.widget.ConstraintLayout>

그리고 데이터베이스 클래스를 만들어줍니다.  DatabaseHelper.java 

package com.example.sqlite_ex;

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

import androidx.annotation.Nullable;

public class DatabaseHelper extends SQLiteOpenHelper {

    public static final String DATABASE_NAME = "STUDENT.db"; // 데이터베이스 명
    public static final String TABLE_NAME = "student_table"; // 테이블 명

    // 테이블 항목
    public static final String COL_1 = "ID";
    public static final String COL_2 = "Name";
    public static final String COL_3 = "Phone";
    public static final String COL_4 = "Address";


    public DatabaseHelper(@Nullable 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, PHONE TEXT, ADDRESS TEXT)");
    }

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

    }

    // 데이터베이스 추가하기 insert

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

    }

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

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

    //데이터베이스 수정하기
    public boolean updateData(String id, String name, String phone, String address){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(COL_1,id);
        contentValues.put(COL_2,name);
        contentValues.put(COL_3,phone);
        contentValues.put(COL_4,address);
        db.update(TABLE_NAME,contentValues,"ID = ?", new String[] { id });
        return true;
    }
}

마지막으로 MainActivity.java 소스코드입니다. 

package com.example.sqlite_ex;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    DatabaseHelper myDB;

    EditText editTextName, editTextPhone, editTextAddress, editTextID;
    Button buttonInsert, buttonView, buttonUpdate, buttonDelete;

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

        myDB = new DatabaseHelper(this);

        editTextName = findViewById(R.id.editTextName);
        editTextPhone = findViewById(R.id.editTextPhone);
        editTextAddress = findViewById(R.id.editTextAddress);
        editTextID = findViewById(R.id.editTextID);

        buttonInsert = findViewById(R.id.buttonInsert);
        buttonView = findViewById(R.id.buttonView);
        buttonUpdate = findViewById(R.id.buttonUpdate);
        buttonDelete =findViewById(R.id.buttonDelete);

        AddData();
        viewAll();
        UpdateData();
        DeleteData();



    }

    //데이터베이스 추가하기
    public void AddData(){
        buttonInsert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                boolean isInserted = myDB.insertData(editTextName.getText().toString(),
                        editTextPhone.getText().toString(),
                        editTextAddress.getText().toString());

                if(isInserted == true)
                    Toast.makeText(MainActivity.this,"데이터추가 성공",Toast.LENGTH_LONG).show();
                else
                    Toast.makeText(MainActivity.this,"데이터추가 실패",Toast.LENGTH_LONG).show();
            }
        });
    }

    // 데이터베이스 읽어오기
    public void viewAll()
    {
        buttonView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Cursor res = myDB.getAllData();
                if(res.getCount() == 0){
                    ShowMessage("실패","데이터를 찾을 수 없습니다.");
                    return;
                }

                StringBuffer buffer = new StringBuffer();
                while(res.moveToNext()){
                    buffer.append("ID: "+res.getString(0)+"\n");
                    buffer.append("이름: "+res.getString(1)+"\n");
                    buffer.append("전화번호: "+res.getString(2)+"\n");
                    buffer.append("주소: "+res.getString(3)+"\n\n");

                }
                ShowMessage("데이터",buffer.toString());


            }
        });

    }

    //데이터베이스 수정하기
    public void UpdateData(){
        buttonUpdate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                boolean isUpdated = myDB.updateData(editTextID.getText().toString(),
                        editTextName.getText().toString(),
                        editTextPhone.getText().toString(),
                        editTextAddress.getText().toString());

                if(isUpdated == true)
                    Toast.makeText(MainActivity.this,"데이터 수정 성공",Toast.LENGTH_LONG).show();
                else
                    Toast.makeText(MainActivity.this,"데이터 수정 실패",Toast.LENGTH_LONG).show();



            }
        });
    }

    // 데이터베이스 삭제하기
    public void DeleteData(){
        buttonDelete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Integer deleteRows = myDB.deleteData(editTextID.getText().toString());
                if(deleteRows>0)
                    Toast.makeText(MainActivity.this,"데이터 삭제 성공",Toast.LENGTH_LONG ).show();
                else
                    Toast.makeText(MainActivity.this,"데이터 삭제 실패",Toast.LENGTH_LONG ).show();
            }
        });
    }




    public void ShowMessage(String title, String Message){
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setCancelable(true);
        builder.setTitle(title);
        builder.setMessage(Message);
        builder.show();
    }


}

이제 제가 안드로이드에서 SQLite CRUD를 구현하는걸 동영상으로 녹화했습니다. 

혼자 중얼중얼 하면서.. ㅋㅋ