Android.基本用法学习笔记

设置文本的内容

先在strings.xml声明变量

方法1.

方法2.

设置文本的大小

1.单位dp，大家可以去学一下有关的单位换算

2.

设置文本颜色

1.

2.

4.设置文本背景颜色

1.

2.

设置视图的宽高

与上级视图一致，也就是上一级有多宽就有多少

1.

2.

3.

4.

设置视图的间距

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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">
    <LinearLayout 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:background="@color/blue"
        android:layout_margin="50sp"
        android:padding="50dp"
        tools:context=".MainActivity">

        <LinearLayout 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:background="@color/red"
            android:layout_margin="50sp"
            tools:context=".MainActivity">
        </LinearLayout>
    </LinearLayout>
    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello"
        android:textSize="40dp"
        android:background="@color/red"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

   <!-- <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="跳转1"
        app:layout_constraintBottom_toTopOf="@id/button2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.501"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/tv" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="跳转2"
        app:layout_constraintTop_toBottomOf="@id/button1"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        />-->


</LinearLayout>

设置视图的对齐方式

线性布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/blue"
android:layout_weight="1"
        android:orientation="horizontal"
        tools:context=".MainActivity"

        >
        <TextView
            android:id="@+id/tv1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/hello"
            android:textSize="30dp"
            android:background="@color/white"

        <TextView
            android:id="@+id/tv2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/hello"
            android:textSize="30dp"
            android:background="@color/red"

    </LinearLayout>
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@color/pink"
        android:orientation="vertical"
        tools:context=".MainActivity"
        android:layout_weight="1"
        >
        <TextView
            android:id="@+id/tv1"
            android:layout_width="wrap_content"

            android:layout_height="wrap_content"
            android:text="@string/hello"
            android:textSize="30dp"
            android:background="@color/green"

        <TextView
            android:id="@+id/tv2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/hello"
            android:textSize="30dp"
            android:background="@color/red"


    </LinearLayout>


    <!-- <Button
         android:id="@+id/button1"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="跳转1"
         app:layout_constraintBottom_toTopOf="@id/button2"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintHorizontal_bias="0.501"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@id/tv" />

     <Button
         android:id="@+id/button2"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="跳转2"
         app:layout_constraintTop_toBottomOf="@id/button1"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintBottom_toBottomOf="parent"
         />-->


</LinearLayout>

相对布局

<?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=".MainActivity">
    <TextView
        android:id="@+id/tv1"
        android:layout_width="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:layout_height="wrap_content"
        android:text="中心"
        android:textSize="40dp"
        android:background="@color/green"/>

    <TextView
    android:id="@+id/tv2"
    android:layout_width="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_alignParentTop="true"
    android:layout_height="wrap_content"
    android:text="中心正上方"
    android:textSize="40dp"
    android:background="@color/green"/>
    <TextView
        android:id="@+id/tv3"
        android:layout_width="wrap_content"
        android:layout_centerVertical="true"
        android:layout_alignParentRight="true"
        android:layout_height="wrap_content"
        android:text="右方"
        android:textSize="40dp"
        android:background="@color/green"/>
    <TextView
        android:id="@+id/tv4"
        android:layout_width="wrap_content"
        android:layout_alignRight="@id/tv3"
        android:layout_height="wrap_content"
        android:text="1"
        android:textSize="40dp"
        android:background="@color/green"/>


</RelativeLayout>

网格布局

<?xml version="1.0" encoding="utf-8"?>
<GridLayout 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:columnCount="2"
    android:rowCount="2"
    tools:context=".MainActivity">


    <TextView
        android:id="@+id/tv4"
        android:layout_width="wrap_content"
        android:layout_columnWeight="1"
        android:layout_height="60dp"
        android:text="1"
        android:textSize="40dp"
        android:gravity="center"
        android:background="@color/green"/>
    <TextView
        android:id="@+id/tv3"
        android:layout_width="wrap_content"
        android:layout_columnWeight="1"
        android:layout_height="60dp"
        android:text="2"
        android:gravity="center"
        android:textSize="40dp"
        android:background="@color/green"/>
    <TextView
        android:id="@+id/tv2"
        android:layout_columnWeight="1"
        android:layout_height="60dp"
        android:text="3"
        android:gravity="center"
        android:textSize="40dp"
        android:background="@color/green"/>
    <TextView
        android:id="@+id/tv1"
        android:layout_columnWeight="1"
        android:layout_height="60dp"
        android:text="4"
        android:gravity="center"
        android:textSize="40dp"
        android:background="@color/green"/>

</GridLayout>

滚动视图

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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:orientation="vertical">

    <HorizontalScrollView
        android:layout_width="wrap_content"
        android:layout_height="200dp">

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="horizontal">

            <View
                android:layout_width="300dp"
                android:layout_height="300dp"
                android:background="@color/green"/>

            <View
                android:layout_width="300dp"
                android:layout_height="300dp"
                android:background="@color/blue" />
        </LinearLayout>
    </HorizontalScrollView>

</LinearLayout>

按钮控件Button

activity xml代码

package com.example.test2;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.ParcelUuid;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class ButtonClickActivity extends AppCompatActivity {

    private TextView tv_result;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_button_click);
        // 找到指定的按钮
        tv_result = findViewById(R.id.tv_result);
        Button buttonclick1 = findViewById(R.id.buttonclick1);
        buttonclick1.setOnClickListener(new MyOnClickListener(tv_result));
    }

    static class MyOnClickListener implements View.OnClickListener {

        private  final TextView tv_result;

        public MyOnClickListener(TextView tv_result) {
            this.tv_result = tv_result;
        }

        @Override
        public void onClick(View v) {

            String desc = String.format("%s 你点击的按钮是: %s", DateUtil.getNowTime(), ((Button)v).getText());
            tv_result.setText(desc);
        }
    }
}

button click java代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".ButtonClickActivity"
    android:orientation="vertical">

    <Button
        android:id="@+id/buttonclick1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="指定单独的点击监听器"
        android:textColor="@color/black"
        android:textSize="15sp"
      />

    <TextView
        android:id="@+id/tv_result"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="5dp"
        android:gravity="center"
        android:textColor="@color/black"
        android:textSize="15dp"
        android:text="点击查看结果"
        />

</LinearLayout>

DateUtil代码

package com.example.test2;

import java.text.SimpleDateFormat;
import java.util.Date;

public class DateUtil {
    public static String getNowTime()
    {
        SimpleDateFormat sdf=new SimpleDateFormat("HH:mm:ss");
        return sdf.format(new Date());


    }
}

Androidmainifest代码

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

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Test2"
        tools:targetApi="31">

        <activity
            android:name=".MainActivity3"
            android:exported="false" />
        <activity
            android:name=".ButtonClickActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".MainActivity2" />

    </application>

</manifest>

图像视图

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