Android Studio development controls and page usage

1. Control

1.1 button

Get button:

Button btn_scan_view=(Button) findViewById(R.id.button_get);

Button click event:

 //Click the start generation button to listen for events
        btn_get.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
//Click event content
            }
        });

1.2 Input box

Input box:

EditText edittext=findViewById(R.id.editTextText);//Input box

Get the input content:

String input= edittext.getText().toString();

1.3 Images

Get the image control:

 ImageView img_view=(ImageView)findViewById(R.id.imageView);

Fill the control with an image:

img_view.setImageBitmap();

2. Page jump

2.1 Jump to custom page

Use Intent to implement page jump
First, we need to create a new Android Activity. In Android Studio, this can be achieved by following these steps:
In the project’s structure view, right-click app -> New -> Activity -> Blank Activity, then name the new Activity and choose which folder to place it in.
In the AndroidManifest.xml file, we need to register a category for the new Activity.

//Listen to the button, if clicked, jump
ntent intent = new Intent();
 //The previous one (MainActivity.this) is the current page, and the next one is the next page to jump to.
 intent.setClass(MainActivity.this,ScanActivity.class);//ScanActivity is modified to the page to be redirected
startActivity(intent);

3. Code example (generate and scan QR code)

3.1 Creating projects and preparations

Create a project and modify the image speedup (settings.gradle.kts) file to:

pluginManagement {
    repositories {
        maven { setUrl("https://maven.aliyun.com/repository/public") }
        maven { setUrl("https://maven.aliyun.com/repository/central") }
        google()
        mavenCentral()
        gradlePluginPortal()
    }
}
dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        maven { setUrl("https://maven.aliyun.com/repository/public") }
        maven { setUrl("https://maven.aliyun.com/repository/central") }
        google()
        mavenCentral()
    }
}

Add the jar package to maven and add in build.gradle.kts:

implementation("com.journeyapps:zxing-android-embedded:3.6.0")

3.2 Main page (generate QR code):

Code:

package com.example.week08_or;
import androidx.appcompat.app.AppCompatActivity;
import android.annotation.SuppressLint;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;

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

import java.util.Hashtable;

public class MainActivity extends AppCompatActivity {
    Button btn_get;
    Button btn_scan_view;
    ImageView img_view;
    EditText edittext;

    @SuppressLint("MissingInflatedId")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn_get=(Button) findViewById(R.id.button_get);
        img_view=(ImageView)findViewById(R.id.imageView);
        btn_scan_view=(Button)findViewById(R.id.button_page);//Jump page
        edittext =findViewById(R.id.editTextText);//input box

        //Click the start generation button to listen for events
        btn_get.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String input= edittext.getText().toString();
                //Call the CreateUtil class to generate a QR code and display it on the interface
                img_view.setImageBitmap(createQRCode(input,img_view.getWidth(),img_view.getHeight()));
            }
        });
        btn_scan_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //Listen to the button, if clicked, jump
                Intent intent = new Intent();
                //The previous one (MainActivity.this) is the current page, and the next one is the next page to jump to.
                intent.setClass(MainActivity.this,ScanActivity.class);
                startActivity(intent);
            }
        });
    }

    //Convert the input string into an image
    public Bitmap createQRCode(String codestring, int width, int height){
        try {
            //First determine the legality of the parameters, requiring that the string content cannot be empty or the image length and width must be greater than 0
            if (TextUtils.isEmpty(codestring)||width<=0||height<=0){
                return null;
            }
            //Set the relevant parameters of the QR code and generate a BitMatrix (bit matrix) object
            Hashtable<EncodeHintType,String> hashtable=new Hashtable<>();
            hashtable.put(EncodeHintType.CHARACTER_SET,"utf-8"); //Set the character transcoding format
            hashtable.put(EncodeHintType.ERROR_CORRECTION,"H"); //Set the fault tolerance level
            hashtable.put(EncodeHintType.MARGIN,"2"); //Set blank margins
            //encode needs to throw and handle exceptions
            BitMatrix bitMatrix=new QRCodeWriter().encode(codestring, BarcodeFormat.QR_CODE,width,height,hashtable);
            //Create a pixel array again and assign color values to the array elements based on the bit matrix
            int[] pixel=new int[width*width];
            for (int h=0;h<height;h + + ){
                for (int w=0;w<width;w + + ){
                    if (bitMatrix.get(w,h)){
                        pixel[h*width + w]= Color.BLACK; //Set black color block
                    }else{
                        pixel[h*width + w]=Color.WHITE; //Set the white color block
                    }
                }
            }
            //Create bitmap object
            //Set the color value of each pixel of Bitmap according to the pixel array, and then return the Bitmap object
            Bitmap qrcodemap=Bitmap.createBitmap(width,height,Bitmap.Config.ARGB_8888);
            qrcodemap.setPixels(pixel,0,width,0,0,width,height);
            return qrcodemap;
        }catch (WriterException e){
            return null;
        }
    }
}

layout file:

<?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">

    <ImageView
        android:id="@ + id/imageView"
        android:layout_width="301dp"
        android:layout_height="283dp"
        android:layout_marginStart="50dp"
        android:layout_marginEnd="50dp"
        android:layout_marginBottom="149dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@ + id/button_get"
        app:layout_constraintVertical_bias="1.0"
        app:srcCompat="@drawable/ic_launcher_background" />

    <Button
        android:id="@ + id/button_get"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="21dp"
        android:layout_marginBottom="529dp"
        android:text="Generate"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@ + id/button_page"
        app:layout_constraintTop_toBottomOf="@ + id/editTextText" />

    <EditText
        android:id="@ + id/editTextText"
        android:layout_width="355dp"
        android:layout_height="78dp"
        android:ems="10"
        android:inputType="text"
        android:text="Enter the string to be generated"
        app:layout_constraintBottom_toTopOf="@ + id/button_page"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@ + id/button_page"
        android:layout_width="108dp"
        android:layout_height="59dp"
        android:layout_marginStart="23dp"
        android:text="Scan code page"
        app:layout_constraintBaseline_toBaselineOf="@ + id/button_get"
        app:layout_constraintEnd_toStartOf="@ + id/button_get"
        app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

3.3 Scan the QR code

Code:

package com.example.week08_or;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import com.google.zxing.integration.android.IntentIntegrator;
import com.google.zxing.integration.android.IntentResult;
import com.journeyapps.barcodescanner.CaptureActivity;


public class ScanActivity extends AppCompatActivity {
    Button btn_scan;
    Button btn_back;
    TextView textView;
    @SuppressLint("MissingInflatedId")
    @Override
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_scan);//Binding page

        btn_scan=(Button)findViewById(R.id.btn_scan);
        btn_back=(Button) findViewById(R.id.button2);
        textView=(TextView)findViewById(R.id.textView);


        //Scan QR code button click event
        btn_scan.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //.QR_CODE_TYPES QR code
                //ONE_D_CODE_TYPES barcode
                //ALL_CODE_TYPES All types
                new IntentIntegrator(ScanActivity.this).setDesiredBarcodeFormats(IntentIntegrator.ALL_CODE_TYPES)//Type of scan code, optional: one-dimensional code, two-dimensional code, one/two-dimensional code
                        .setPrompt("Please aim at the QR code")//Set prompt
                        .setCameraId(0)//Select the camera, you can use front or rear
                        .setBeepEnabled(false)//Whether to turn on the sound, there will be a "beep" after scanning the code
                        //.setBarcodeImageEnabled(true)// Generate a QR code image after scanning the code
                        .setCaptureActivity(CaptureActivity.class)
                        .initiateScan();//Initialize code scanning
            }
        });
        //return to previous page
        btn_back.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });
    }
#Callback function to process scan results
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
        if(result != null) {
            if(result.getContents() == null) {
                Toast.makeText(this, "Cancelled", Toast.LENGTH_LONG).show();
            } else {
                Toast.makeText(this, "Scanned: " + result.getContents(), Toast.LENGTH_LONG).show();
                textView.setText(result.getContents());
            }
        } else {
            super.onActivityResult(requestCode, resultCode, data);
        }
    }
}

Layout file:

<?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">

    <Button
        android:id="@ + id/btn_scan"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="104dp"
        android:layout_marginBottom="90dp"
        android:text="Scan"
        app:layout_constraintBottom_toTopOf="@ + id/textView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@ + id/textView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="55dp"
        android:layout_marginEnd="55dp"
        android:layout_marginBottom="275dp"
        android:text="Scan results"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@ + id/btn_scan" />

    <Button
        android:id="@ + id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="33dp"
        android:layout_marginTop="5dp"
        android:text="Return"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@ + id/btn_scan" />
</androidx.constraintlayout.widget.ConstraintLayout>

3.2.3 Customized scan window

need to

setCaptureActivity(CaptureActivity.class)

change into:

setCaptureActivity(CustomCaptureActivity.class)
//CustomCaptureActivity is the custom activity name.

Activity:

package com.example.week08_or;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.KeyEvent;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import com.journeyapps.barcodescanner.CaptureManager;
import com.journeyapps.barcodescanner.DecoratedBarcodeView;

public class CustomCaptureActivity extends AppCompatActivity {
    private CaptureManager capture;
    private DecoratedBarcodeView barcodeScannerView;

    @SuppressLint("MissingInflatedId")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_custom_capture); // Custom layout

        barcodeScannerView = (DecoratedBarcodeView) findViewById(R.id.dbv_custom);

        capture = new CaptureManager(this, barcodeScannerView);
        capture.initializeFromIntent(getIntent(), savedInstanceState);
        capture.decode();
    }

    @Override
    protected void onResume() {
        super.onResume();
        capture.onResume();
    }

    @Override
    protected void onPause() {
        super.onPause();
        capture.onPause();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        capture.onDestroy();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        capture.onSaveInstanceState(outState);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[], @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        capture.onRequestPermissionsResult(requestCode, permissions, grantResults);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        return barcodeScannerView.onKeyDown(keyCode, event) || super.onKeyDown(keyCode, event);
    }
}

layout:

<?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">

    <com.journeyapps.barcodescanner.DecoratedBarcodeView
        android:id="@ + id/dbv_custom"
        android:layout_width="372dp"
        android:layout_height="683dp"
        android:layout_marginStart="20dp"
        android:layout_marginEnd="20dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:zxing_preview_scaling_strategy="fitXY"
        tools:layout_editor_absoluteY="19dp"
        tools:ignore="MissingConstraints" />

</androidx.constraintlayout.widget.ConstraintLayout>