找不到类’android.graphics.drawable.RippleDrawable’,无法执行android的方法:onClick,Android Studio

我正在尝试制作一个用于订购咖啡的应用程序。 (我真的很陌生。)

我的应用程序运行正常,直到出现两个错误。 现在,它在设备中运行,但是当您尝试触摸按钮时,它会停止。

代码是:

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代码:

     

终端中的第一个错误:

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

而主要的错误:

 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) 

改变这一行

 quantityTextView.setText(number); 

对此:

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

要么:

  quantityTextView.setText(number+"");