Build a QR (Quick Response Code) Generator and Reader Android App in Android Studio

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Build a QR (Quick Response Code) Generator and Reader Android App in Android Studio

java code

package com.example.myqrcodegenerator;

import android.graphics.Bitmap;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import androidx.appcompat.app.AppCompatActivity;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;

public class MainActivity extends AppCompatActivity {
    private EditText editText;
    private ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        editText = findViewById(R.id.editText);
        imageView = findViewById(R.id.imageView);
    }

    public void QRCodeButton(View view){
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        try {
            BitMatrix bitMatrix = qrCodeWriter.encode(editText.getText().toString(), BarcodeFormat.QR_CODE, 200, 200);
            Bitmap bitmap = Bitmap.createBitmap(200, 200, Bitmap.Config.RGB_565);
            for (int x = 0; x<200; x++){
                for (int y=0; y<200; y++){
                    bitmap.setPixel(x,y,bitMatrix.get(x,y)? Color.BLACK : Color.WHITE);
                }
            }
            imageView.setImageBitmap(bitmap);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

xml code

<?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:layout_marginStart="150dp"
        android:layout_marginTop="83dp"
        android:onClick="QRCodeButton"
        android:text="@string/qr_code"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/editText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="85dp"
        android:layout_marginTop="52dp"
        android:ems="10"
        android:hint="@string/enter_the_text_here"
        android:inputType="textPersonName"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button"
        android:autofillHints="" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_marginStart="105dp"
        android:layout_marginTop="85dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editText"
        app:srcCompat="?attr/actionBarDivider"
        android:contentDescription="@string/todo" />
</androidx.constraintlayout.widget.ConstraintLayout>

apply plugin: 'com.android.application'

android {
    compileSdkVersion 29
    defaultConfig {
        applicationId "com.example.myqrcodegenerator"
        minSdkVersion 28
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.appcompat:appcompat:1.0.2'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.0'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'

    implementation 'com.google.zxing:core:3.2.1'
}

Final Words

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