How to make your own custom keyboard (OS system level) for all the Apps of your Android device?

In this video it shows steps to create your own custom keyboard for Android device. The keyboard shown in this demo is system level keyboard and will work across any App of your Android device. It makes an entry at the system level and can be configured to be used in the settings of the Android device.

I hope you like this video. For any questions, suggestions or appreciation please contact us at: https://programmerworld.co/contact/ or email at: programmerworld1990@gmail.com

Complete source code and other details:

No change required in MainActivity.java code

package com.programmerworld.customkeyboardsystemlevel;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

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

New Java class – CustomKeyboardApp

package com.programmerworld.customkeyboardsystemlevel;

import android.inputmethodservice.InputMethodService;
import android.inputmethodservice.Keyboard;
import android.inputmethodservice.KeyboardView;
import android.view.View;
import android.view.inputmethod.InputConnection;

public class CustomKeyboardApp extends InputMethodService
        implements KeyboardView.OnKeyboardActionListener {

    @Override
    public View onCreateInputView() {
        KeyboardView keyboardView = (KeyboardView) getLayoutInflater().inflate(R.layout.custom_keyboard_layout, null);
        Keyboard keyboard = new Keyboard(this, R.xml.custom_keypad);
        keyboardView.setKeyboard(keyboard);

        keyboardView.setOnKeyboardActionListener(this);
        return keyboardView;
    }

    @Override
    public void onPress(int i) {
    }

    @Override
    public void onRelease(int i) {
    }

    @Override
    public void onKey(int i, int[] ints) {
        InputConnection inputConnection = getCurrentInputConnection();
        if (inputConnection == null){
            return;
        }
        inputConnection.commitText(String.valueOf((char) i),1);
    }

    @Override
    public void onText(CharSequence charSequence) {
    }

    @Override
    public void swipeLeft() {
    }

    @Override
    public void swipeRight() {
    }

    @Override
    public void swipeDown() {
    }

    @Override
    public void swipeUp() {
    }
}

Layout Files:

<?xml version="1.0" encoding="utf-8"?>
<android.inputmethodservice.KeyboardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:keyPreviewLayout="@layout/custom_keyboard_preview"

    android:layout_alignParentBottom="true">

</android.inputmethodservice.KeyboardView>

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white"
    android:gravity="center"
    android:textColor="@color/black"
    android:textSize="24sp">

</TextView>

XML Files:

<?xml version="1.0" encoding="utf-8"?>
<Keyboard xmlns:android="http://schemas.android.com/apk/res/android"
    android:horizontalGap="5dp"
    android:verticalGap="5dp"
    android:keyHeight="60dp"
    android:keyWidth="20%p">


    <Row>
        <Key android:keyLabel="1" android:keyEdgeFlags="left"/>
        <Key android:keyLabel="2"/>
        <Key android:keyLabel="3"/>
        <Key android:keyLabel="4"/>
        <Key android:keyLabel="5" android:keyEdgeFlags="right"/>
    </Row>

    <Row>
        <Key android:keyLabel="6" android:keyEdgeFlags="left"/>
        <Key android:keyLabel="7"/>
        <Key android:keyLabel="8"/>
        <Key android:keyLabel="9"/>
        <Key android:keyLabel="0" android:keyEdgeFlags="right"/>
    </Row>

    <Row
        android:keyWidth="33%p">
        <Key android:keyLabel="A" android:keyEdgeFlags="left"/>
        <Key android:keyLabel="B"/>
        <Key android:keyLabel="C" android:keyEdgeFlags="right"/>
    </Row>

</Keyboard>

<?xml version="1.0" encoding="utf-8"?>
<input-method xmlns:android="http://schemas.android.com/apk/res/android">

    <subtype android:imeSubtypeMode = "keyboard"/>

</input-method>

Manifest file:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.CustomKeyBoardSystemLevel"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <service android:name=".CustomKeyboardApp"
            android:label="Programmer World Keyboard"
            android:permission="android.permission.BIND_INPUT_METHOD"
            android:exported="true">
            <intent-filter>
                <action android:name="android.view.InputMethod"/>
            </intent-filter>
            <meta-data
                android:name="android.view.im"
                android:resource="@xml/custom_method"/>
        </service>
        
    </application>
</manifest>

Screenshots: