CODE EXAMPLE FOR JAVA

Android Change Text Of Button On Click

package com.example.f3;

import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity extends AppCompatActivity {

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

    public void onClick(View view){

Button btn       = (Button)findViewById(R.id.button);

btn.setText("HELLO WORLD");
    }
}