Android按钮控制加减，，（购物车中的加减器）

<? 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" android :orientation= "vertical" tools :context= "com.example.com.zhangjinlong0514.MainActivity"> < LinearLayout android :layout_width= "match_parent" android :layout_height= "match_parent" android :orientation= "horizontal"> < Button android :layout_width= "wrap_content" android :layout_height= "wrap_content" android :layout_weight= "1" android :id= "@+id/but1" android :text= "-"/> < TextView android :layout_width= "wrap_content" android :layout_height= "wrap_content" android :layout_weight= "1" android :id= "@+id/tv" android :text= "12条数据"/> < Button android :layout_width= "wrap_content" android :layout_height= "wrap_content" android :layout_weight= "1" android :id= "@+id/but2" android :text= "+"/>LinearLayout> < com.example.com.zhangjinlong0514.MyViewGroup android :layout_width= "match_parent" android :layout_height= "wrap_content" android :layout_marginTop= "200dp" > < TextView android :layout_width= "150dp" android :layout_height= "40dp" android :background= "#f00" /> < TextView android :layout_width= "150dp" android :layout_height= "40dp" android :background= "#02fac0" /> < TextView android :layout_width= "150dp" android :layout_height= "40dp" android :background= "#0033ff" /> com.example.com.zhangjinlong0514.MyViewGroup> RelativeLayout>

package com.example.com.zhangjinlong0514; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.TextView; public class MainActivity extends AppCompatActivity { private Button but1; private Button but2; private int a= 0; private int b; private TextView tv; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate( savedInstanceState); setContentView(R.layout. activity_main); but1 = findViewById(R.id. but1); but2 = findViewById(R.id. but2); tv = findViewById(R.id. tv); but2.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View view) { b= a+ 1; a= b; tv.setText( ""+ b); } }); but1.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View view) { if( b> 0){ b--; tv.setText( ""+ b); } } }); } } 购物车中的加减器：

运用组合式控件编写一个类似于购物车的增加删除数量的效果，如图所示：

MainActivity中

public class MainActivity extends AppCompatActivity {    private viewjia av;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        av = (viewjia) findViewById(R.id.jia);        av.setMaxValue(10);        av.setOnNumberChangerListener(new viewjia.OnNumberChangerListener() {            @Override            public void OnNumberChanger(int value) {                //属于我自己的业务逻辑                Toast.makeText(MainActivity.this, "变化的数量值"+value, Toast.LENGTH_SHORT).show();            }        });    }}

类继承一个属于ViewGroup下的任意自定义控件

public class viewjia extends LinearLayout implements View.OnClickListener {    private ImageButton mIv_sub;    private ImageButton mIv_add;    private TextView mTv_value;    private int mValue;    //1.创建对象的时候    public viewjia(Context context) {        this(context, null);    }    //2.XML中使用的时候回调    public viewjia(Context context, AttributeSet attrs) {        this(context, attrs ,  0);    }    //3.在XML中使用,且使用Style风格中.    public viewjia(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        initView(context);    }    private void initView(Context context) {        //把一个布局文件实例化,并且加载到AddSuVIew类中        View inflate = View.inflate(context, R.layout.item, this);        //初始化控件        mIv_sub = (ImageButton) inflate.findViewById(iv_sub);        mIv_add = (ImageButton) inflate.findViewById(iv_add);        mTv_value = (TextView) inflate.findViewById(tv_value);        mIv_add.setOnClickListener(this);        mIv_sub.setOnClickListener(this);        //获取Value值        int value = getValue();        //设置valus的值        setValue(value);    }    //当前数量值,默认为1,设置对此值获取.    private int value =1;    private int mMaxValue =5;    private int mMinValue =1;    public void setMaxValue(int maxValue) {        mMaxValue = maxValue;    }    /**     * 这里获取Value是从UI那里拿到值     * @return     */    public int getValue() {        String trim = mTv_value.getText().toString().trim();        if (!TextUtils.isEmpty(trim)){            //获取出来,因为其值是字符串,所以要进行Int型转换            value =Integer.valueOf(trim);        }        return value;    }    public void setValue(int value) {        mValue = value;        mTv_value.setText(value+"");    }    //ImageView按钮的点击事件    @Override    public void onClick(View view) {        switch (view.getId()) {            //添加            case iv_add:                addNumber();                break;            //减少            case iv_sub:                subNumber();                break;            default:                break;        }    }    private void addNumber() {        if (value < mMaxValue)        {            value++;        }        setValue(value);        if (mOnNumberChangerListener !=null){            mOnNumberChangerListener.OnNumberChanger(value);        }    }    private void subNumber() {        if (value > mMinValue){            value--;        }        setValue(value);        //当按钮是Value值发生变化时,回调该接口方法        if (mOnNumberChangerListener !=null){            mOnNumberChangerListener.OnNumberChanger(value);        }    }    /**     * B.定义接口,及所要调用的接口方法,当商品数量发生变化时,回调给接口     */    public interface OnNumberChangerListener{        void OnNumberChanger(int value);    }    //定义接口对象    private OnNumberChangerListener mOnNumberChangerListener;    //设置方法接收外界传来的接口对象方法    public void setOnNumberChangerListener(OnNumberChangerListener onNumberChangerListener){        mOnNumberChangerListener =onNumberChangerListener;    }}

MainXML

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main"    android:layout_width="match_parent" android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.example.view_.MainActivity"    android:orientation="horizontal"><com.example.view_.viewjia    android:id="@+id/jia"    android:layout_width="wrap_content"    android:layout_height="wrap_content">com.example.view_.viewjia>LinearLayout>

自定义控件的布局

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="horizontal">    <ImageButton        android:id="@+id/iv_add"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:src="@mipmap/b"/>    <TextView        android:id="@+id/tv_value"        android:layout_width="50dp"        android:layout_height="50dp"        android:gravity="center"        android:textSize="20sp"        android:text="1"/>    <ImageButton        android:id="@+id/iv_sub"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:src="@mipmap/a"/>LinearLayout>

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