How to create a dynamic array button in Android?

Question

I have a button. I want to write the function "onClick" for the button. Each time that I click on it I want a new button to be created on screen. And also that new button to be added into an array list of buttons.

I searched but I couldn't find any answer. All of the answers talk about creating buttons with drop and drag, not with dynamic creation of them.

Thanks

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Click to add"
        android:id="@+id/B1"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:onClick="clicktoaddcode"
        />
</RelativeLayout>

package com.example.yas.dynamicbutton;

import android.support.v7.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 clicktoaddcode(View V){
        Toast.makeText(MainActivity.this, "Created", Toast.LENGTH_SHORT).show();
    }
}

You're going to need to make your question a lot more clear and provide the code you have so far plus what is/isn't happening to receive a good answer. — codeMagic
– codeMagic, Commented Oct 18, 2015 at 4:05

Mohammad Hossein Gerami · Accepted Answer · 2015-10-20 04:16:56Z

2

You must using ArrayList.

List<Button> btnList = new ArrayList<>();

// Call Your ClickListener
btnList.add(new Button(YourContext));
YourParent.addView(btnList.get(btnList.size() - 1 ));

Edited

MainActivity.java

public class MainActivity extends AppCompatActivity {

    LinearLayout container;

    List<Button> btnList = new ArrayList<>();

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

        container = (LinearLayout)findViewById(R.id.container);


    }

    public void addBtn(View v){
        btnList.add(new Button(this));
        container.addView(btnList.get(btnList.size() - 1 ));
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    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" android:fitsSystemWindows="true"
    tools:context=".MainActivity">

    <LinearLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:clickable="true"
        android:onClick="addBtn">

    </LinearLayout>

</android.support.design.widget.CoordinatorLayout>

edited Oct 20, 2015 at 4:16

answered Oct 18, 2015 at 4:04

Mohammad Hossein Gerami

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9 Comments

Malus Jan Over a year ago

in "YourContext" and "YourParent" what should I write?

Mohammad Hossein Gerami Over a year ago

instead of YourContext you must set your activity instance and YourParent is main layout that you want add Button inside it

Malus Jan Over a year ago

would you please send me a small example? XML file and mainactivity.java thank you

Malus Jan Over a year ago

Thanks. I did it but I have a question: TextView T = new TextView(MainActivity.this); T.setText(Hello); setContentView(T); the textview appear on the button that I hade. I want to have 81 textview 9*9 like.

Mohammad Hossein Gerami Over a year ago

where is your question?! it's just description

|

Girish Raman · Accepted Answer · 2015-10-18 09:12:08Z

1

Have this for your XML -

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center">

        <Button
            android:id="@+id/myButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Add one more" />

        <LinearLayout
            android:orientation="vertical"
            android:id="@+id/myLinearLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center">

        </LinearLayout>

    </LinearLayout>
</ScrollView>

And this in Java-

final LinearLayout linearLayout = (LinearLayout)findViewById(R.id.myLinearLayout);
    Button button = (Button)findViewById(R.id.myButton);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Button button = new Button(MainActivity.this);
            button.setText("A new Button");
            linearLayout.addView(button);
        }
    });

answered Oct 18, 2015 at 9:12

Girish Raman

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3 Comments

Malus Jan Over a year ago

When I run it: unfortuately Program name has stoped.

Girish Raman Over a year ago

You should know to use the Log to find what's going wrong. This piece of code works just fine. There's gotta be some other issue with other parts of your code.

Malus Jan Over a year ago

E/AndroidRuntime: java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.yas.dbutton/com.example.yas.dbutton.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.Window.findViewById(int)' on a null object reference

Zia · Accepted Answer · 2020-02-14 10:03:49Z

The most simple method to create an unlimited size array is using String Builder. This allows you to add many elements in runtime. It has 3 major components.

Declaration and Initialization.
Value addition/ Append
Print out/ Usage

Use the bellow code anywhere in Android Studio.

//Basic Decleration
        StringBuilder myString = new StringBuilder();
        
//Adding data
       myString.append("Hello text <br>");
        myString.append("some more data <br>");
        myString.append("more data to store <br>");
        
//Displaying in already created text view
        deviceDetails.setText(Html.fromHtml(callLogs+""));

Note: I'm treating this as HTML string and " " tags will create the next line in text view. So, all added data will be displayed in a new line.

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