studyjams大餐之： justjava 第一版

1 目标

2 过程

code

package com.example.android.justjava;

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

import java.text.NumberFormat;

/**
* This app displays an order form to order coffee.
*/
public class MainActivity extends ActionBarActivity {

// Number of cups of coffee ordered
int quantity = 2;

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

/**
* This method is called when the plus button is clicked.
*/
public void increment(View view) {
quantity = quantity + 1;
display(quantity);
}

/**
* This method is called when the minus button is clicked.
*/
public void decrement(View view) {
quantity = quantity - 1;
display(quantity);
}

/**
* This method is called when the order button is clicked.
*/
public void submitOrder(View view) {
int price = quantity * 5;
String priceMessage = "这是最简单的android demo: $" + price;
priceMessage = priceMessage + "\n期待更多交互功能加入!";
displayMessage(priceMessage);
}

/**
* 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);
}

/**
* This method displays the given price value on the screen.
*/
private void displayPrice(int number) {
TextView priceTextView = (TextView) findViewById(R.id.price_text_view);
priceTextView.setText(NumberFormat.getCurrencyInstance().format(number));
}

/**
* This method displays the given text on the screen.
*/
private void displayMessage(String message) {
TextView priceTextView = (TextView) findViewById(R.id.price_text_view);
priceTextView.setText(message);
}

}

layout

<!-- 这是正规的注释方法
-->
<LinearLayout 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"
android:orientation="vertical"
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=".MainActivity"
android:weightSum="1">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="16dp"
android:text="Quantity"
android:textAllCaps="true" />

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

<Button
android:layout_width="48dp"
android:layout_height="48dp"
android:onClick="decrement"
android:text="-" />

<TextView
android:id="@+id/quantity_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="8dp"
android:paddingRight="8dp"
android:text="2"
android:textColor="@android:color/black"
android:textSize="16sp" />

<Button
android:layout_width="48dp"
android:layout_height="48dp"
android:onClick="increment"
android:text="+" />

</LinearLayout>

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Price"
android:textAllCaps="true" />

<TextView
android:id="@+id/price_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="$10"
android:textColor="@android:color/black"
android:textSize="16sp" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:onClick="submitOrder"
android:text="Order" />

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="titer1@qq.com"
android:textColor="@android:color/black"
android:textSize="16sp"
android:layout_marginBottom="16dp"
/>

<ImageView
android:layout_width="190dp"
android:layout_height="wrap_content"
android:id="@+id/imageView"
android:layout_weight="0.55"
android:src="@mipmap/ic_launcher"
/>

</LinearLayout>

3 实现截图

4思考