Android 作业05

<?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:id="@+id/bg"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    tools:ignore="InvalidId">

    <Button
        android:id="@+id/bt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="80dp"
        android:layout_marginRight="80dp"
        android:layout_marginBottom="408dp"
        android:background="#cccccc"
        android:onClick="click"
        android:text="  Change the background color  "
        android:textColor="#ffffff"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        tools:ignore="MissingConstraints,OnClick" />

</androidx.constraintlayout.widget.ConstraintLayout>

package com.example.myapplication1;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.content.DialogInterface;
import android.graphics.Color;
import android.os.Bundle;
import android.text.style.BackgroundColorSpan;
import android.view.View;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    String ba="000000";
    public void click(View view){
        AlertDialog dialog;
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("color");
        builder.setIcon(R.drawable.ic_launcher_background);
        builder.setSingleChoiceItems(new String[]{"orange", "blue", "pink", "green"}, 0, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                switch(which){
                    case 0:
                        ba="#ffba8f";
                        break;
                    case 1:
                        ba="#98caec";
                        break;
                    case 2:
                        ba="fca0c9";
                        break;
                    case 3:
                        ba="bbe094";
                        break;
                }

            }
        });
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                (findViewById(R.id.bg)).setBackgroundColor(Color.parseColor(ba));
                dialog.dismiss();
            }
        });
        builder.setNegativeButton("cancel", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        dialog=builder.create();
        dialog.show();
    }
}