我想创建一个简单的测试应用程序，基本上是通过从外部JAR文件调用一些简单的功能，扩展了Android的Hello World教程应用程序。然而，当我运行的应用程序，它找不到从JAR中的类。我究竟做错了什么？

I am trying to create a simple test app that basically extends the Android Hello World tutorial app by invoking some simple functionality from an external JAR. However, when I run the app, it can't find the class from the JAR. What am I doing wrong?

下面是JAR的整个源：

Here's entire source of the JAR:

package com.mytests.pow;

public class power2 {

private double d;   

public power2()
{
    d = 0.0;
}   

public String stp2(double dd) 
{
    d = dd*dd;
    return String.format("%e", d);
}

}

和这里的的Hello World ++来源：

And here's the "Hello World ++" source:

package com.myLuceneTests.namespace;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

import com.mytests.pow.*;

public class AndroidSimpleSIH_EclipseActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {

    power2 pp = new power2();
    String iout = pp.stp2(12.0);

    super.onCreate(savedInstanceState);
    TextView tv = new TextView(this);
    tv.setText(iout);
    setContentView(tv);

}
}

当我运行应用程序时，我得到这个logcat的：

When I run the app, I get this in logcat:

11-22 12:24:52.697  2963  2963 E dalvikvm: Could not find class 'com.mytests.pow.power2', referenced from method com.myLuceneTests.namespace

.AndroidSimpleSIH_EclipseActivity.onCreate

.AndroidSimpleSIH_EclipseActivity.onCreate

然后

11-22 12:24:52.713  2963  2963 E AndroidRuntime: java.lang.NoClassDefFoundError: com.mytests.pow.power2

我是什么做错了吗？谢谢！

What am I doing wrong? Thanks!

顺便说一句，我的实际目标是用真实的JAR（而不是这个玩具的）在一个Android应用程序。我可能有机会获得code为JAR，可能能够重建它，但它是一个很大的一块的Java code和我有可能重建的时候，所以我想使用的$ P遇到的问题$ P-JAR建

By the way, my actual goal is to use a real JAR (rather than this toy one) in an Android app. I might have access to the code for that JAR and might be able to rebuild it but it's a big piece of Java code and I am likely to encounter problems when rebuilding it so I am trying to use the pre-built JAR.

推荐答案

有没有必要建立外部罐子。尝试从您的构建路径中删除并按照下列步骤操作：

There's no need to build the external jar. Try removing it from your build path and follow these steps:

在你的Andr​​oid项目叫根目录下创建一个文件夹库。 的jar添加到该文件夹​​。 右键单击该罐，然后单击添加到构建路径。 清理项目，然后重试。 Create a folder in the root of your Android project called libs. Add the jar to that folder. Right-click the jar and click to add to build path. Clean your project and try it again.