android 五、六周作业

1.返回键实现对话框弹出是否退出应用程序

package cn.itcast.myapplication;

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

import android.content.DialogInterface;
import android.os.Bundle;

public class Main5Activity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main5);
    }
    public void onBackPressed(){
        AlertDialog dialog;
        AlertDialog.Builder builder=new AlertDialog.Builder(this);
        builder.setTitle("普通对话框");
        builder.setIcon(R.mipmap.ic_launcher);
        builder.setMessage("是否退出应用");
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog,int which) {
                dialog.dismiss();
                Main5Activity.this.finish();
            }
        });
        
        builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog,int which) {
              dialog.dismiss();
            }
        });
        dialog=builder.create();
        dialog.show();



    }



}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="match_parent"
    android:layout_width="match_parent">
<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="按钮1"
    android:layout_centerInParent="true"
    android:background="#777BB9">

</Button>
</RelativeLayout>

2.实现以下场景：从一个activity中点击一个按钮后，弹出一个单选按钮对话框，上面有“男”“女”两个选项，选定后，TOAST弹出 你选择了男，或你选择了女（参考书上改字体）

<RelativeLayout  xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="match_parent"
    android:layout_width="match_parent">
    <Button
        android:id="@+id/But_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="请选择性别"
        android:background="#E49C9C"
        android:textSize="25dp"
        android:layout_centerInParent="true"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="单选对话框"
        android:textSize="30dp"
        android:background="#8EACB4"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="100dp"/>


</RelativeLayout>

package cn.itcast.singchoice;

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

import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private Button But_1;
    private int num=0;


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

        findViewById( R.id.But_1 ).setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        AlertDialog.Builder builder=new AlertDialog.Builder( this )
                .setTitle( "选择性别" )
                .setSingleChoiceItems( new String[]{"男", "女"}, -1, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        num=i;
                    }
                } )
                .setPositiveButton( "确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int i) {
                        if (num==0){
                            Toast.makeText( MainActivity.this,"您选择的是男",Toast.LENGTH_SHORT ).show();
                        }else {
                            Toast.makeText( MainActivity.this,"您选择的是女",Toast.LENGTH_LONG ).show();
                        }
                        dialog.dismiss();
                    }
                } )
                .setNegativeButton( "取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int i) {
                        dialog.dismiss();

                    }
                } );
        AlertDialog dialog = builder.create();
        dialog.show();

    }
}

 

3.布局(详见:Android第五周上机word文档)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:background="#FFFDDd">
    <TextView
        android:id="@+id/Tv_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="1.TextView显示文本信息"
        android:textColor="#1E27B1"
        android:textSize="25dp"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"/>

    <Button
        android:id="@+id/But_1"
        android:layout_width="350dp"
        android:layout_height="wrap_content"
        android:layout_marginLeft="30dp"
        android:text="2.按钮"
        android:background="#FFFFFF"
        android:textColor="#1E27B1"
        android:textSize="25dp"
        android:layout_below="@id/Tv_1"/>
    <EditText
        android:id="@+id/Edi_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="3.编辑框：请输入信息"
        android:textColor="#1E27B1"
        android:layout_marginTop="100dp"
        android:layout_marginLeft="30dp"
        android:textSize="25dp"/>
    <RadioGroup
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:layout_marginTop="170dp"
        android:layout_marginLeft="30dp">
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="25dp"
            android:textColor="#1E27B1"
            android:text="男"/>
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="25dp"
            android:textColor="#1E27B1"
            android:text="女"/>

    </RadioGroup>
    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <CheckBox
            android:id="@+id/Che_1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="25dp"
            android:textColor="#1E27B1"
            android:text="电脑"
            android:layout_marginLeft="30dp"
            android:layout_marginTop="200dp"/>

        <CheckBox
            android:id="@+id/Che_2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="25dp"
            android:textColor="#1E27B1"
            android:text="手机"
            android:layout_marginLeft="30dp"
            />
    </LinearLayout>



</RelativeLayout>