安卓第七周作业

1.三个界面，界面1点击按钮使用显式意图开启界面2.
界面2点击按钮隐式意图开启界面3

public class MainActivity extends AppCompatActivity {
    private Button b_1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.text71);
        b_1=(Button) findViewById(R.id.b_1);
        b_1.setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View v) {
                Intent intent=new Intent(MainActivity.this,Main2Activity.class);
                startActivity(intent);
                Toast.makeText(MainActivity.this,"已开启界面2",Toast.LENGTH_LONG).show();
            }
        });
    }

public class Main2Activity extends AppCompatActivity {

    private Button b_2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        b_2=(Button) findViewById(R.id.b_2);
        b_2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent=new Intent();
                intent.setAction("android.intent.action.MAIN3");
                intent.addCategory("android.intent.category.DEFAULT");
                startActivity(intent);
                Toast.makeText(Main2Activity.this,"已开启界面3",Toast.LENGTH_LONG).show();
            }
        });
    }
}

public class Main3Activity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main3);

    }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapplication">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".Main3Activity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN3" />

                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
        <activity android:name=".Main2Activity" />
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/b_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="点击开启界面2"
        android:layout_centerInParent="true"/>

</RelativeLayout>

<?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"
    tools:context=".Main2Activity">

    <Button
        android:id="@+id/b_2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="点击开启界面3"
        android:layout_centerInParent="true"/>

</RelativeLayout>

<?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"
    tools:context=".Main3Activity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="这里是界面3"
        android:textSize="20dp"
        android:textColor="#000000"
        android:layout_centerInParent="true"/>

</RelativeLayout>

 

 

 2.在界面1做一个按钮开启浏览器访问百度

 

    public void onClick2(View v){
        Intent intent=new Intent();
        intent.setAction("android.intent.action.VIEW");
        intent.setData(Uri.parse("http://www.baidu.com"));
        startActivity(intent);
        Toast.makeText(MainActivity.this,"已开启百度",Toast.LENGTH_LONG).show();
    }

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">

<Button
    android:id="@+id/b_1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="点击开启界面2"
    android:layout_centerInParent="true"/>

    <Button
        android:id="@+id/b_2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="点击打开百度"
        android:layout_below="@+id/b_1"
        android:layout_centerHorizontal="true"
        android:onClick="onClick2"/>

</RelativeLayout>

 

 

3.2个edittext,4个按钮一个textview，实现简单计算器。

提示1：如何获取edittext上的数据？
String num1=((EditText)(findViewById(R.id.et1))).getText().toString();//获取et1上面的文本，并
转成字符串
提示2：字符串如何转int
int n1=Integer.parseInt(num1);
提示3:如何把计算结果显示在textview上？
TextView tv1=(TextView)findViewById(R.id.tv1);//获取控件
tv1.setText("1233213");//用settext方法赋值

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.text71);

        findViewById(R.id.b_1).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                String num1=((EditText)(findViewById(R.id.ediText1))).getText().toString();
                String num2=((EditText)(findViewById(R.id.ediText2))).getText().toString();
                int n1=Integer.parseInt(num1);
                int n2=Integer.parseInt(num2);
                int n3=n1+n2;
                TextView tv=(TextView)findViewById(R.id.tv);
                tv.setText("计算结果是:"+n3);
                Toast.makeText(MainActivity.this,"加法结果"+n3,Toast.LENGTH_LONG).show();
            }
        });

        findViewById(R.id.b_2).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                String num1=((EditText)(findViewById(R.id.ediText1))).getText().toString();
                String num2=((EditText)(findViewById(R.id.ediText2))).getText().toString();
                int n1=Integer.parseInt(num1);
                int n2=Integer.parseInt(num2);
                int n3=n1-n2;
                TextView tv=(TextView)findViewById(R.id.tv);
                tv.setText("计算结果是:"+n3);
                Toast.makeText(MainActivity.this,"减法结果"+n3,Toast.LENGTH_LONG).show();
            }
        });

        findViewById(R.id.b_3).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                String num1=((EditText)(findViewById(R.id.ediText1))).getText().toString();
                String num2=((EditText)(findViewById(R.id.ediText2))).getText().toString();
                int n1=Integer.parseInt(num1);
                int n2=Integer.parseInt(num2);
                int n3=n1*n2;
                TextView tv=(TextView)findViewById(R.id.tv);
                tv.setText("计算结果是:"+n3);
                Toast.makeText(MainActivity.this,"乘法结果"+n3,Toast.LENGTH_LONG).show();
            }
        });

        findViewById(R.id.b_4).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                String num1=((EditText)(findViewById(R.id.ediText1))).getText().toString();
                String num2=((EditText)(findViewById(R.id.ediText2))).getText().toString();
                int n1=Integer.parseInt(num1);
                int n2=Integer.parseInt(num2);
                int n3=n1/n2;
                TextView tv=(TextView)findViewById(R.id.tv);
                tv.setText("计算结果是:"+n3);
                Toast.makeText(MainActivity.this,"除法结果"+n3,Toast.LENGTH_LONG).show();
            }
        });
    }

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">

    <EditText
        android:id="@+id/ediText1"
        android:layout_width="300dp"
        android:layout_height="70dp"
        android:layout_marginBottom="10dp"
        android:hint="请输入数1"
        android:textSize="30dp"/>

    <EditText
        android:id="@+id/ediText2"
        android:layout_below="@id/ediText1"
        android:layout_width="300dp"
        android:layout_height="70dp"
        android:layout_marginBottom="10dp"
        android:hint="请输入数2"
        android:textSize="30dp"/>

    <Button
        android:id="@+id/b_1"
        android:layout_below="@id/ediText2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="+"
        android:textSize="20dp"/>

    <Button
        android:id="@+id/b_2"
        android:layout_below="@id/ediText2"
        android:layout_toRightOf="@id/b_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="-"
        android:textSize="20dp"/>

    <Button
        android:id="@+id/b_3"
        android:layout_below="@id/ediText2"
        android:layout_toRightOf="@id/b_2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="*"
        android:textSize="20dp"/>

    <Button
        android:id="@+id/b_4"
        android:layout_below="@id/ediText2"
        android:layout_toRightOf="@id/b_3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="/"
        android:textSize="20dp"/>

    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="60dp"
        android:layout_below="@id/b_1"
        android:textSize="30dp"/>

</RelativeLayout>