创建和声明变量

创建变量
```
 int total;
```
初始化变量值
```
 total = 10;
```

int total = 10;

style.xml

负责引用基本样式，设置默认View的样式，如

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">#ff9800</item>
    <item name="colorPrimaryDark">#ff9800</item>
    <item name="colorButtonNormal">#ff9800</item>
</style>

在布局中插入分割线

<View
    android:layout_width="1dp"
    android:layout_height="match_parent"
    android:background="@android:color/darker_gray"/>

Count Counter App 源码

activity_main.xml

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

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

        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:orientation="vertical">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center_horizontal"
                android:padding="16dp"
                android:fontFamily="sans-serif-medium"
                android:textColor="#616161"
                android:textSize="14sp"
                android:text="Team A" />

            <TextView
                android:id="@+id/team_a_score"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center_horizontal"
                android:paddingBottom="4dp"
                android:fontFamily="sans-serif-light"
                android:textSize="56sp"
                android:textColor="#000"
                android:text="0" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                android:layout_marginLeft="24dp"
                android:layout_marginRight="24dp"
                android:onClick="addThreeForTeamA"
                android:text="+3 Points" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                android:layout_marginLeft="24dp"
                android:layout_marginRight="24dp"
                android:onClick="addTwoForTeamA"
                android:text="+2 Points" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                android:layout_marginLeft="24dp"
                android:layout_marginRight="24dp"
                android:onClick="addOneForTeamA"
                android:text="Free Throw" />

        </LinearLayout>

        <View
            android:layout_width="1dp"
            android:layout_marginTop="16dp"
            android:layout_height="match_parent"
            android:background="@android:color/darker_gray"/>

        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:orientation="vertical">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center_horizontal"
                android:padding="16dp"
                android:text="Team B"
                android:fontFamily="sans-serif-medium"
                android:textColor="#616161"
                android:textSize="14sp"/>

            <TextView
                android:id="@+id/team_b_score"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center_horizontal"
                android:paddingBottom="4dp"
                android:fontFamily="sans-serif-light"
                android:textSize="56sp"
                android:textColor="#000"
                android:text="0" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                android:layout_marginLeft="24dp"
                android:layout_marginRight="24dp"
                android:onClick="addThreeForTeamB"
                android:text="+3 Points" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                android:layout_marginLeft="24dp"
                android:layout_marginRight="24dp"
                android:onClick="addTwoForTeamB"
                android:text="+2 Points" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                android:layout_marginLeft="24dp"
                android:layout_marginRight="24dp"
                android:onClick="addOneForTeamB"
                android:text="Free Throw" />

        </LinearLayout>
    </LinearLayout>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="8dp"
        android:layout_marginLeft="24dp"
        android:layout_marginRight="24dp"
        android:onClick="reset"
        android:text="Reset" />

</RelativeLayout>

Main_Activity.java
package com.example.clixin.countcounter;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

import org.w3c.dom.Text;

public class MainActivity extends AppCompatActivity {

    int scoreTeamA = 0;
    int scoreTeamB = 0;

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

    public void displayForTeamA(int score) {
        TextView scoreView = (TextView) findViewById(R.id.team_a_score);
        scoreView.setText(String.valueOf(score));
    }

    public void addThreeForTeamA(View view) {
        scoreTeamA = scoreTeamA + 3;
        displayForTeamA(scoreTeamA);
    }

    public void addTwoForTeamA(View view) {
        scoreTeamA = scoreTeamA + 2;
        displayForTeamA(scoreTeamA);
    }

    public void addOneForTeamA(View view) {
        scoreTeamA = scoreTeamA + 1;
        displayForTeamA(scoreTeamA);
    }

    public void displayForTeamB(int score) {
        TextView scoreView = (TextView) findViewById(R.id.team_b_score);
        scoreView.setText(String.valueOf(score));
    }

    public void addThreeForTeamB(View view) {
        scoreTeamB = scoreTeamB + 3;
        displayForTeamB(scoreTeamB);
    }

    public void addTwoForTeamB(View view) {
        scoreTeamB = scoreTeamB + 2;
        displayForTeamB(scoreTeamB);
    }

    public void addOneForTeamB(View view) {
        scoreTeamB = scoreTeamB + 1;
        displayForTeamB(scoreTeamB);
    }

    public void reset(View view) {
        scoreTeamA = 0;
        scoreTeamB = 0;
        displayForTeamA(scoreTeamA);
        displayForTeamB(scoreTeamB);
    }
}

效果图