找不到類'android.graphics.drawable.RippleDrawable'，無法爲android執行方法：onClick，Android Studio

Question

我正在嘗試訂購咖啡的應用程序。 （我真的很新鮮）

我的應用程序工作完美，直到出現兩個錯誤。現在，它運行在一個設備上，但是當您嘗試觸摸按鈕時，它會停止。

的代碼是：

package com.example.android.justjava; 
import android.os.Bundle; 
import android.support.v7.app.AppCompatActivity; 
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 AppCompatActivity { 
    int quantity = 0; 
    //int priceOfOneCup = 5; 

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

    /** 
    * This method is called when the order button is clicked. 
    */ 
    public void submitOrder(View view){ 
     //calculatePrice(quantity, priceOfOneCup); 
     int price = quantity * 5 ; 
     String priceMessage = "Total: " + price + "€" + "\nThank You!"; 
     displayMessage(priceMessage); 
    } 

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

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


    /** 
    * This method displays the given quantity value on the screen. 
    */ 
    private void displayQuantity(int number) { 
     TextView quantityTextView = (TextView) findViewById(R.id.quantity_text_view); 
     quantityTextView.setText(number); 
    } 

    /** 
    * This method displays the given price 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); 
    } 

XML代碼：

<?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:orientation="vertical" 
    android:padding="16dp" 
    tools:context="com.example.android.justjava.MainActivity"> 

    <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"> 

     <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:layout_marginLeft="8dp" 
      android:layout_marginRight="8dp" 
      android:text="0" 
      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_marginBottom="16dp" 
     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:text="Total: 0€" 
     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" /> 
    </LinearLayout> 

在終端的第一個錯誤：

E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering 

和主錯誤：

E/AndroidRuntime: FATAL EXCEPTION: main 
      Process: com.example.android.justjava, PID: 32585 
      java.lang.IllegalStateException: Could not execute method for android:onClick 
       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293) 
       at android.view.View.performClick(View.java:4508) 
       at android.view.View$PerformClick.run(View.java:18675) 
       at android.os.Handler.handleCallback(Handler.java:733) 
       at android.os.Handler.dispatchMessage(Handler.java:95) 
       at android.os.Looper.loop(Looper.java:136) 
       at android.app.ActivityThread.main(ActivityThread.java:5584) 
       at java.lang.reflect.Method.invokeNative(Native Method) 
       at java.lang.reflect.Method.invoke(Method.java:515) 
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268) 
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084) 
       at dalvik.system.NativeStart.main(Native Method) 
      Caused by: java.lang.reflect.InvocationTargetException 
       at java.lang.reflect.Method.invokeNative(Native Method) 
       at java.lang.reflect.Method.invoke(Method.java:515) 
       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
       at android.view.View.performClick(View.java:4508)  
       at android.view.View$PerformClick.run(View.java:18675)  
       at android.os.Handler.handleCallback(Handler.java:733)  
       at android.os.Handler.dispatchMessage(Handler.java:95)  
       at android.os.Looper.loop(Looper.java:136)  
       at android.app.ActivityThread.main(ActivityThread.java:5584)  
       at java.lang.reflect.Method.invokeNative(Native Method)  
       at java.lang.reflect.Method.invoke(Method.java:515)  
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)  
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)  
       at dalvik.system.NativeStart.main(Native Method)  
      Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x1 
       at android.content.res.Resources.getText(Resources.java:1404) 
       at android.support.v7.widget.ResourcesWrapper.getText(ResourcesWrapper.java:52) 
       at android.widget.TextView.setText(TextView.java:4262) 
       at com.example.android.justjava.MainActivity.displayQuantity(MainActivity.java:61) 
       at com.example.android.justjava.MainActivity.increment(MainActivity.java:44) 
       at java.lang.reflect.Method.invokeNative(Native Method)  
       at java.lang.reflect.Method.invoke(Method.java:515)  
       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)  
       at android.view.View.performClick(View.java:4508)  
       at android.view.View$PerformClick.run(View.java:18675)  
       at android.os.Handler.handleCallback(Handler.java:733)  
       at android.os.Handler.dispatchMessage(Handler.java:95)  
       at android.os.Looper.loop(Looper.java:136)  
       at android.app.ActivityThread.main(ActivityThread.java:5584)  
       at java.lang.reflect.Method.invokeNative(Native Method)  
       at java.lang.reflect.Method.invoke(Method.java:515)  
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)  
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)  
       at dalvik.system.NativeStart.main(Native Method) 

Answer 1

改變這一行

quantityTextView.setText(number); 

這樣：

quantityTextView.setText(String.valueOf(number)); 

或：

quantityTextView.setText(number+"");