Android：week 7总结 Dialog、单选对话框

目录

1.Dialog

2.单选对话框

---

 

1.Dialog

 

引入的几个头文件！

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.view.KeyEvent;
 

package com.example.dialog;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.view.KeyEvent;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    @Override
    public void onBackPressed() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("退出提示");
        builder.setIcon(R.mipmap.ic_launcher);
        builder.setMessage("你确定要退出吗？");
        //确定退出
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();  //退出对话框
                MainActivity.this.finish();  //退出界面
            }
        });

        //取消退出
        builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();  //退出对话框
            }
        });
        AlertDialog alertDialog = builder.create();     //创建界面
        alertDialog.show();//显示界面
    }
}

 

2.单选对话框(改变字体大小)

引入的头文件

import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

 

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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:text="Hello world! 你好，世界！"
        android:textSize="15sp"
        android:gravity="center">
    </TextView>
    <Button
        android:id="@+id/bt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toBottomOf="@id/tv"
        android:text="改变字体大小"
        android:textSize="15sp"
        android:layout_marginTop="5sp">
    </Button>

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java 

package com.example.dialog;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    private TextView textView;
    private Button button;
    private int index=0;  //下标
    private int[] textSize = new int[]{10,20,30,40,50}; //字体大小
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = findViewById(R.id.tv);
        button = findViewById(R.id.bt);
        button.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("字体大小");
        builder.setIcon(R.mipmap.ic_launcher);

        //设置单选列表      ①字符列表  ②选中的编号  ③接口
        builder.setSingleChoiceItems(new String[]{"10", "20", "30", "40", "50"}, 0, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {    //which 选中哪一行的下标(从0开始)
                index=which;

            }
        });

        builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                textView.setTextSize(textSize[index]);
                dialog.dismiss();
            }
        });
        builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });

        //生成一个对话框
        AlertDialog alertDialog = builder.create();     //创建界面
        alertDialog.show();//显示界面
    }

    @Override
    public void onBackPressed() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("退出提示");
        builder.setIcon(R.mipmap.ic_launcher);
        builder.setMessage("你确定要退出吗？");
        //确定退出
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();  //退出对话框
                MainActivity.this.finish();  //退出界面
            }
        });

        //取消退出
        builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();  //退出对话框
            }
        });
        AlertDialog alertDialog = builder.create();     //创建界面
        alertDialog.show();//显示界面
    }
}