Android，從導入的jar文件中找不到類

Question

我在我的Android項目中包含了一個jar文件，如How can I use external JARs in an Android project?中所述。在這篇文章中，MannyNS和Vinayak B描述了這兩種方法，我得到錯誤「找不到類」test.libraryCalc.Calc「，這是圖書館提供的類。下面的代碼說明了此問題：

實施例經由庫提供類：Calc.java

package test.libraryCalc; 

public class Calc { 
    public int add(int a, int b){ 
     return a + b; 
    } 
} 

LibraryTestActivity.java

package test.library; 

import test.libraryCalc.Calc; 
import android.app.Activity; 
import android.os.Bundle; 

public class LibraryTestActivity extends Activity { 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     Calc calc = new Calc(); 
     int c = calc.add(3, 4); 
    } 
} 

我出口含有Calc.java到LibraryTest \庫jar文件\ calc.jar

並在LibraryTest

Java構建路徑中添加對它的引用使用「添加JAR文件...」按鈕，該圖書館展示了在引用的庫中LibraryTest

LibraryTest沒有構建問題，但在模擬器上運行時，它的下面是logcat中顯示：

12-27 14:01:33.965: E/dalvikvm(747): Could not find class 'test.libraryCalc.Calc',    referenced from method test.library.LibraryTestActivity.onCreate 
12-27 14:01:33.965: W/dalvikvm(747): VFY: unable to resolve new-instance 13 (Ltest/libraryCalc/Calc;) in Ltest/library/LibraryTestActivity; 
12-27 14:01:33.995: D/dalvikvm(747): VFY: replacing opcode 0x22 at 0x0008 
12-27 14:01:33.995: D/dalvikvm(747): VFY: dead code 0x000a-0013 in Ltest/library/LibraryTestActivity;.onCreate (Landroid/os/Bundle;)V 
12-27 14:01:34.065: D/AndroidRuntime(747): Shutting down VM 
12-27 14:01:34.065: W/dalvikvm(747): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 
12-27 14:01:34.075: E/AndroidRuntime(747): FATAL EXCEPTION: main 
12-27 14:01:34.075: E/AndroidRuntime(747): java.lang.NoClassDefFoundError: test.libraryCalc.Calc 
12-27 14:01:34.075: E/AndroidRuntime(747): at  test.library.LibraryTestActivity.onCreate(LibraryTestActivity.java:14) 
12-27 14:01:34.075: E/AndroidRuntime(747): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
12-27 14:01:34.075: E/AndroidRuntime(747): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 
12-27 14:01:34.075: E/AndroidRuntime(747): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 
12-27 14:01:34.075: E/AndroidRuntime(747): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 
12-27 14:01:34.075: E/AndroidRuntime(747): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 
12-27 14:01:34.075: E/AndroidRuntime(747): at android.os.Handler.dispatchMessage(Handler.java:99) 
12-27 14:01:34.075: E/AndroidRuntime(747): at android.os.Looper.loop(Looper.java:123) 
12-27 14:01:34.075: E/AndroidRuntime(747): at android.app.ActivityThread.main(ActivityThread.java:4627) 
12-27 14:01:34.075: E/AndroidRuntime(747): at java.lang.reflect.Method.invokeNative(Native Method) 
12-27 14:01:34.075: E/AndroidRuntime(747): at java.lang.reflect.Method.invoke(Method.java:521) 
12-27 14:01:34.075: E/AndroidRuntime(747): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
12-27 14:01:34.075: E/AndroidRuntime(747): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
12-27 14:01:34.075: E/AndroidRuntime(747): at dalvik.system.NativeStart.main(Native Method) 
12-27 14:06:34.170: I/Process(747): Sending signal. PID: 747 SIG: 9 

需要採取哪些措施來得到這個工作？感謝您的所有建議。

Answer 1

我認爲問題在於您嘗試添加包含Android代碼的jar。你不可以做這個。要包含Android代碼，您應該創建Android庫。只需創建一個Android項目，並在項目屬性Android部分設置這是庫項目。之後，您可以將此庫添加到您的項目中。有關Android庫的更多信息，請閱讀here。

更新：我試過你的代碼了。它適用於我的情況。我所做的唯一區別是在導出Jar期間我檢查了導出Java源文件和資源。希望這會幫助你。嘗試一下！