Monday, August 31, 2015

How to show an indeterminate ProgressBar in Android

MainActivity.java

package com.cfsuman.androidtutorials;

import android.os.Bundle;
import android.app.Activity;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;


public class MainActivity extends Activity {
    private int progressStatus = 0;
    private Handler handler = new Handler();

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

        // Get the widgets reference from XML layout
        Button button = findViewById(R.id.button);
        ProgressBar progressBar = findViewById(R.id.progressBar);
        TextView textView = findViewById(R.id.textView);


        // Set a click listener for Button widget
        button.setOnClickListener(view -> {
            // Disable the button itself
            view.setEnabled(false);

            // Set the progress status zero on each button click
            progressStatus = 0;
            // Visible the progress bar and text view
            progressBar.setVisibility(View.VISIBLE);
            textView.setVisibility(View.VISIBLE);

            // Start the lengthy operation in a background thread
            new Thread(new Runnable() {
                @Override
                public void run() {
                    while (progressStatus < 100) {
                        // Update the progress status
                        progressStatus += 1;

                        // Try to sleep the thread for 20 milliseconds
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }

                        // Update the progress bar
                        handler.post(new Runnable() {
                            @Override
                            public void run() {
                                progressBar.setProgress(progressStatus);
                                // Show the progress on TextView
                                textView.setText(progressStatus + "");
                                // If task execution completed
                                if (progressStatus == 100) {
                                    // Hide the progress bar from layout
                                    // after finishing task
                                    progressBar.setVisibility(View.GONE);
                                    // Set a message of completion
                                    textView.setText("Operation completed.");

                                    // Enable the button itself
                                    view.setEnabled(true);
                                }
                            }
                        });
                    }
                }
            }).start(); // Start the operation
        });
    }
}
activity_main.xml

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:tools="http://schemas.android.com/tools"
    android:background="#DCDCDC"
    android:padding="24dp">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="64dp"
        android:fontFamily="sans-serif"
        android:textSize="24sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:text="TextView" />

    <ProgressBar
        android:id="@+id/progressBar"
        style="@android:style/Widget.Holo.Light.ProgressBar.Horizontal"
        android:visibility="gone"
        android:indeterminate="true"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_below="@id/textView"
        android:layout_marginTop="16dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="Start Task"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/progressBar" />

</androidx.constraintlayout.widget.ConstraintLayout>