我的应用程序崩溃了。 不幸的是应用已经停止
我是一名新的Android开发人员，正在研究Udacity Beginners课程中的JustJava应用程序。 使用我的手机来调试我的代码，当我点击按钮更新价格时，它会给出错误：“不幸的是JustJava已停止”。
AndroidManifest.xml中
MainActivity.java
import android.icu.text.NumberFormat; import android.os.Build; import android.os.Bundle; import android.support.annotation.RequiresApi; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.TextView; /** * This app displays an order form to order coffee. */ public class MainActivity extends AppCompatActivity { @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) { display(2); displayPrice(2 * 5); } /** * 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 on the screen. */ private void displayPrice(int number) { TextView priceTextView = (TextView) findViewById(R.id.price_text_view); priceTextView.setText (NumberFormat.getCurrencyInstance().format(number)); } }
activity_main.xml中
Logcat错误：
04-25 09:22:04.944 449-449/com.example.android.justjava E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.justjava, PID: 449 java.lang.IllegalStateException: Could not execute method for android:onClick at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293) at android.view.View.performClick(View.java:4470) at android.view.View$PerformClick.run(View.java:18773) at android.os.Handler.handleCallback(Handler.java:808) at android.os.Handler.dispatchMessage(Handler.java:103) at android.os.Looper.loop(Looper.java:193) at android.app.ActivityThread.main(ActivityThread.java:5341) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:830) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:646) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.reflect.InvocationTargetException at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) at android.view.View.performClick(View.java:4470) at android.view.View$PerformClick.run(View.java:18773) at android.os.Handler.handleCallback(Handler.java:808) at android.os.Handler.dispatchMessage(Handler.java:103) at android.os.Looper.loop(Looper.java:193) at android.app.ActivityThread.main(ActivityThread.java:5341) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:830) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:646) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.NoClassDefFoundError: android.icu.text.NumberFormat at com.example.android.justjava.MainActivity.displayPrice(MainActivity.java:49) at com.example.android.justjava.MainActivity.submitOrder(MainActivity.java:33) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) at android.view.View.performClick(View.java:4470) at android.view.View$PerformClick.run(View.java:18773) at android.os.Handler.handleCallback(Handler.java:808) at android.os.Handler.dispatchMessage(Handler.java:103) at android.os.Looper.loop(Looper.java:193) at android.app.ActivityThread.main(ActivityThread.java:5341) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515)
错误是相当具体的。 根本原因是在堆栈跟踪的末尾：
Caused by: java.lang.NoClassDefFoundError: android.icu.text.NumberFormat at com.example.android.justjava.MainActivity.displayPrice(MainActivity.java:49) at com.example.android.justjava.MainActivity.submitOrder(MainActivity.java:33)
类加载器可能没有找到您在应用程序中使用的android.icu.text.NumberFormat类定义。
您应该检查手机上安装的Android版本是否与仅自API 24（Android 7.0）以来可用的此类兼容。
https://developer.android.com/reference/android/icu/text/NumberFormat.html