練習1 Just Java

標籤：version   auto   order   deb   event   code   XML   super   value   

    

任務：做這樣一個介面，選擇數量，自動計算價格。超級簡單。。

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout 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        android:layout_width="match_parent"        android:layout_height="match_parent"        android:padding="16dp"        android:orientation="vertical">        <TextView            android:id="@+id/quantityText_text_view"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="Quantity"            android:textColor="@android:color/darker_gray"/>        <LinearLayout            android:layout_width="match_parent"            android:layout_height="wrap_content">            <Button                android:layout_width="48dp"                android:layout_height="wrap_content"                android:text="+"                android:onClick="increment" />            <TextView                android:id="@+id/quantity_text_view"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="0"                android:textSize="16sp"                android:paddingLeft="8dp"                android:paddingRight="8dp"                android:textColor="@android:color/black" />            <Button                android:layout_width="48dp"                android:layout_height="wrap_content"                android:text="-"                android:onClick="decrement"/>        </LinearLayout>        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="Price"            android:textColor="@android:color/darker_gray"/>        <TextView            android:id="@+id/price_text_view"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:textColor="@android:color/black"            android:textSize="16sp"            android:text="$0"/>        <Button            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="ORDER"            android:onClick="submitOrder"            tools:ignore="OnClick" />    </LinearLayout></android.support.constraint.ConstraintLayout>

介面

package com.learn.nianhao.justjava;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 number =0;    int price = 5;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        display(number);        displayPrice(number*price);    }    /**     * This method is called when the order button is clicked.     */    public void submitOrder(View view) {        display(number);        displayPrice(number*price);    }    /**     * This method displays the given quantity value on the screen.     */    private void display(int number) {        TextView quantityTextView = (TextView) findViewById(R.id.quantity_text_view);        quantityTextView.setText("" + number);    }    private void displayPrice(int price){        TextView priveTextView = (TextView) findViewById(R.id.price_text_view);        priveTextView.setText("$"+price);    }    public void increment(View view) {        number+=1;        display(number);        displayPrice(number*price);    }    public void decrement(View view) {        if(number>0){            number-=1;            display(number);            displayPrice(number*price);        }    }}

響應類

 

練習1 Just Java