Question

我在Android上使用SimpleDateFormat。我用API 24对它进行了测试，结果很有效。当我尝试在API 16上使用它时它会崩溃。我在互联网上搜索过，我发现有人说这可能是因为导入声明错误（import android.icu.text.SimpleDateFormat），但我已经在使用import java.text.SimpleDateFormat。

我的代码（它在onclickButton上崩溃）：

import java.text.SimpleDateFormat;

public class MainActivity extends AppCompatActivity {

SimpleDateFormat sdf;
String date;

    public void onclickButton (View view) {

        Calendar c = Calendar.getInstance();
        sdf = new SimpleDateFormat("dd MM YYYY");
        sdf.setTimeZone(TimeZone.getTimeZone("Europe/Berlin"));
        date = sdf.format(c.getTime());
    }
...
}

堆栈跟踪：

W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0xb111d228)
E/AndroidRuntime: FATAL EXCEPTION: main
              java.lang.IllegalStateException: Could not execute method for android:onClick
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
                  at android.view.View.performClick(View.java:4084)
                  at android.view.View$PerformClick.run(View.java:16966)
                  at android.os.Handler.handleCallback(Handler.java:615)
                  at android.os.Handler.dispatchMessage(Handler.java:92)
                  at android.os.Looper.loop(Looper.java:137)
                  at android.app.ActivityThread.main(ActivityThread.java:4745)
                  at java.lang.reflect.Method.invokeNative(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:511)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
                  at dalvik.system.NativeStart.main(Native Method)
               Caused by: java.lang.reflect.InvocationTargetException
                  at java.lang.reflect.Method.invokeNative(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:511)
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
                  at android.view.View.performClick(View.java:4084) 
                  at android.view.View$PerformClick.run(View.java:16966) 
                  at android.os.Handler.handleCallback(Handler.java:615) 
                  at android.os.Handler.dispatchMessage(Handler.java:92) 
                  at android.os.Looper.loop(Looper.java:137) 
                  at android.app.ActivityThread.main(ActivityThread.java:4745) 
                  at java.lang.reflect.Method.invokeNative(Native Method) 
                  at java.lang.reflect.Method.invoke(Method.java:511) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
                  at dalvik.system.NativeStart.main(Native Method) 
               Caused by: java.lang.IllegalArgumentException: Unknown pattern character 'Y'
                  at java.text.SimpleDateFormat.validateFormat(SimpleDateFormat.java:268)
                  at java.text.SimpleDateFormat.validatePattern(SimpleDateFormat.java:323)
                  at java.text.SimpleDateFormat.<init>(SimpleDateFormat.java:369)
                  at java.text.SimpleDateFormat.<init>(SimpleDateFormat.java:253)
                  at com.jonathan_tilly.adventskalender.MainActivity.onclickButton(MainActivity.java:34)
                  at java.lang.reflect.Method.invokeNative(Native Method) 
                  at java.lang.reflect.Method.invoke(Method.java:511) 
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
                  at android.view.View.performClick(View.java:4084) 
                  at android.view.View$PerformClick.run(View.java:16966) 
                  at android.os.Handler.handleCallback(Handler.java:615) 
                  at android.os.Handler.dispatchMessage(Handler.java:92) 
                  at android.os.Looper.loop(Looper.java:137) 
                  at android.app.ActivityThread.main(ActivityThread.java:4745) 
                  at java.lang.reflect.Method.invokeNative(Native Method) 
                  at java.lang.reflect.Method.invoke(Method.java:511) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
                  at dalvik.system.NativeStart.main(Native Method)

感谢任何帮助！

Answer 1

可能是因为你在课堂上声明了变量。尝试：

import java.text.SimpleDateFormat;

public class MainActivity extends AppCompatActivity {

    SimpleDateFormat sdf;
    String date;

    public void onclickButton (View view) {

        Calendar c = Calendar.getInstance();
        sdf = new SimpleDateFormat("dd MM yyyy");
        sdf.setTimeZone(TimeZone.getTimeZone("Europe/Berlin"));
        date = sdf.format(c.getTime());
    }
...

}

Answer 2

我认为你应该使用

new SimpleDateFormat("dd MM yyyy");

而不是

new SimpleDateFormat("dd MM YYYY");

它对我有用

而且java doc说YYYY是一周的 Here

Android：SimpleDateFormat提供API错误

2 个答案: