Click Button Show text or image in Android Studio | Learn Android Studio...

Xml Code:- 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/edt"/>

    <TextView
        android:id="@+id/txt"
        android:textSize="30sp"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text=""
       />
<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:text="Show"
    android:id="@+id/btn"/>
</LinearLayout>

Java Code:-  

package com.niranjan.buttonclick;

import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity extends AppCompatActivity {
TextView textView;
Button button;
EditText editText;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView=findViewById(R.id.txt);
        editText=findViewById(R.id.edt);
        button=findViewById(R.id.btn);
      button.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              String name = editText.getText().toString();
             if (name.isEmpty()){
                 textView.setText("Hello Niranjan");
             }else {
                 textView.setText(name);
             }
          }
      });

    }
}