上一篇的ProgressBar練習是以Horizont的方式
這篇是以環形轉圈圈的ProgressBar練習
利用按下Button後跳出Progress Bar，類似現在許多介面換頁都會以ProgressBar顯示
首先先在Activity_main.xml新增一個Login的Button
範例如下：

<?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" >
    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="100dp"
        android:text="LOGIN"
        android:textSize="50dp" />
</LinearLayout>

接著在res/layout下新增一個xml檔來設計按下Button後跳出Progress Bar的樣式

<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ProgressBar
        android:id="@+id/progressBar"
        style="?android:attr/progressBarStyle"
        android:layout_width="100sp"
        android:layout_height="100sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.41" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="Loading..."
        android:textSize="30dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/progressBar" />
</androidx.constraintlayout.widget.ConstraintLayout>

設計完Progress Bar後先新增一個java檔來設定跳出的Progress Bar的時間

package com.example.itprogress2;

import android.app.Activity;
import android.app.AlertDialog;
import android.view.LayoutInflater;

public class login {
    private Activity activity;
    private AlertDialog alertDialog;

    login(Activity myactivity) {
        activity = myactivity;
    }
    void startlogin(){
        AlertDialog.Builder builder = new AlertDialog.Builder(activity);
        LayoutInflater inflater = activity.getLayoutInflater();
        builder.setView(inflater.inflate(R.layout.in,null));
        //等於true時滑鼠點一下即可暫停
        //等於false時則不會暫停
        builder.setCancelable(true);

        alertDialog = builder.create();
        alertDialog.show();
    }
    void dismisslogin(){
        alertDialog.dismiss();
    }
}

接著回到MainActivity.java來設定Button按下時的設定

package com.example.itprogress2;

import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity extends AppCompatActivity {
    Button button;


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

        button = (Button)findViewById(R.id.button);
        login login = new login(MainActivity.this);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                login.startlogin();
            }
        });

    }
}

這樣就好囉