Android Fifth jobs

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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:id="@+id/rl1"
    tools:context=".MainActivity">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="点击下方按钮\n更换背景颜色"
        android:textColor="#ff3300ff"
        android:textSize="35sp"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="150dp"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="按钮"
        android:textSize="39sp"
        android:background="#66cccccc"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"
        android:onClick="test"
        />
</RelativeLayout>

package com.example.workfive;

import android.content.DialogInterface;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    String[] a = {"#CC3300", "#FFFF00", "#3300FF", "#33CC33", "#9900CC"};
    int b = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate (savedInstanceState); 
        the setContentView (R.layout.activity_main); 
    } 
    public  void Test (View View) { 
        AlertDialog Dialog; 
        AlertDialog.Builder Builder = new new AlertDialog.Builder ( the this ) 
                .setTitle ( "set the font size")            // provided the title 
                .setIcon (R.drawable.ic_launcher_background) 
                .setSingleChoiceItems ( new new String [] { "red", "yellow", "blue", "green", "purple"}, B, new new DialogInterface.
                    OnClickListener() {
                    public void onClick(DialogInterface dialog, int Which) {
                         // event that occurs when the point radio buttons, radio buttons showing Which here you are several points 
                        B = Which; 
                    } 
                }) 
                .setPositiveButton ( "OK", new new DialogInterface.OnClickListener () { 
                    @ override 
                    public  void the onClick (DialogInterface Dialog, int Which) {
                         // event that occurs when the point determination button 
                        the findViewById (R.id.rl1) .setBackgroundColor (Color.parseColor (a [B])); 
                        dialog.dismiss (); 
                    } 
                }) //Add "OK" button 
                .setNegativeButton ( "Cancel", new new DialogInterface.OnClickListener () { 
                    @Override 
                    public  void the onClick (DialogInterface Dialog, int Which) {
                         // point cancel button event occurred 
                        dialog.dismiss (); 
                    } 
                }); 
        Dialog = Once builder.create (); 
        with dialog.show (); 

    } 


}