java - NoClassDefFoundError : com/google/common/base/Preconditions, 但先决条件在我的运行时类路径中的 .jar 文件中

Question

我有一个使用 Guava 的 ImmutableList 和 ImmutableSet 的项目。它编译得很好，但在运行时，使用相同的 -cp，它给出了这个错误信息:

Exception in thread "main" java.lang.NoClassDefFoundError: com/google/common/base/Preconditions
    at com.google.common.collect.RegularImmutableList.get(RegularImmutableList.java:81)
    at BasicPoint.pointAsArray(BasicPoint.java:93)
    at BasicPoint.inflate(BasicPoint.java:134)
    at BasicEdgeLength.<clinit>(BasicEdgeLength.java:32)
Caused by: java.lang.ClassNotFoundException: com.google.common.base.Preconditions
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 4 more

我用这个命令在终端编译它

javac -cp '.:/MYPROJECTDIRECTORY/guava-14.0.1.jar'  BasicEdgeLength.java

然后编译。然后我用这个命令运行它

java -cp '.:/MYPROJECTDIRECTORY/guava-14.0.1.jar'  BasicEdgeLength

我收到上述错误消息。有other questions在 stackoverflow 上关于完全相同的问题，但答案总是下载我已经完成的 Guava 库。事实上，当我在 guava-14.0.1.jar 中四处闲逛时，我可以看到文件 com/google/common/base/Preconditions。事实上，我可以在 .jar 文件中看到错误消息中提到的类，这让我想象我无法通过下载更多文件来解决这个问题。所以我不确定该怎么做，如果您能提供任何建议，我将不胜感激。

我在下面包含了 BasicPoint 的代码，因为这是调用 RegularImmutableList.get(i) 的类，但请注意 BasicPoint 不会编译没有 AbstractPoint、IntMatrix、Initializer 和可能的其他一些东西(并且它不包含 main 方法，可以在 基本边长)。如果有人认为有必要，我很乐意将代码附加到其他一些类中。

谢谢大家的宝贵时间!

/**
*    This class implements a point.
*    It uses a representation as a vector of integers.  
*/

import com.google.common.collect.*;
//import com.google.common.base.*; // same error occurs whether or not I include this line

final public class BasicPoint implements AbstractPoint<BasicPoint, BasicAngle> {

// static variables for all points.
private static final int length = Initializer.N - 1;

private static final IntMatrix ROT = Initializer.ROT;

private static final IntMatrix REF = Initializer.REF;

private static final IntMatrix INFL = Initializer.INFL;

// A vector identifying the point.  
private final ImmutableList<Integer> point;

// Constructor methods.

private BasicPoint(Integer[] vector) {
    if (vector.length != length) {
        throw new IllegalArgumentException("Point length is incorrect.");
    }
    this.point = ImmutableList.copyOf(vector);
}

private BasicPoint() {
    Integer[] vector = new Integer[length];
    for (int i = 0; i < length; i++) {
        vector[i] = 0;
    }
    point = ImmutableList.copyOf(vector);
}

// public static factory method
static public BasicPoint createBasicPoint(Integer[] vector) {
    return new BasicPoint(vector);
}

static final public BasicPoint zeroVector() {
    return new BasicPoint();
}

static final public BasicPoint unitVector() {
    Integer[] vector = new Integer[length];
    vector[0] = 1;
    for (int i = 1; i < length; i++) {
        vector[i] = 0;
    }
    return new BasicPoint(vector);
}

// toString method.
public String toString() {
    String outString = "(";
    for (int i = 0; i < point.size() - 1; i++) {
        outString = outString + point.get(i) + ",";
    }
    outString = outString + point.get(length) + ")";
    return outString;
}

// equals method.
public boolean equals(Object obj) {
    if (obj == null || getClass() != obj.getClass())
        return false;
    BasicPoint p = (BasicPoint) obj;
    for (int i = 0; i < length; i++) {
        if (p.point.get(i) != this.point.get(i))
            return false;
    }
    return true;
}

// hashCode override.
public int hashCode() {
    int prime = 53;
    int result = 11;
    for (int i = 0; i < length; i++) {
        result = prime*result + point.get(i);
    }
    return result;
}

// a private helper method to turn point into an array of Integers.
private Integer[] pointAsArray() {
    Integer[] output = new Integer[length];
    for (int i = 0; i < length; i++)
        output[i] = point.get(i);
    return output;
}

// Manipulation methods.  
public BasicPoint add(BasicPoint p) {
    Integer[] q = new Integer[length];
    for (int i = 0; i < length; i++) {
        q[i] = this.point.get(i) + p.point.get(i);
    }
    return new BasicPoint(q);
}

public BasicPoint scalarMultiple(int c) {
    Integer[] q = new Integer[length];
    for (int i = 0; i < length; i++) {
        q[i] = c * this.point.get(i);
    }
    return new BasicPoint(q);
}

public BasicPoint subtract(BasicPoint p) {
    return this.add(p.scalarMultiple(-1));
}

public BasicPoint rotate(BasicAngle a) {
    int i = a.getAsInt();
    if (i < 0)
        throw new IllegalArgumentException("You must perform a positive number of rotations.");

    Integer[] result  = new Integer[length];
    for (int j = 0; j < i; j++)
        result = ROT.rowTimes(result);
    return new BasicPoint(result);
}

public BasicPoint reflect() {
    return new BasicPoint(REF.rowTimes(this.pointAsArray()));
}

public BasicPoint inflate() {
    return new BasicPoint(INFL.rowTimes(this.pointAsArray()));
}

} // end of class BasicPoint

Answer 1

一位 friend 查看了我项目中的文件并为我确定了问题所在。他注意到我的 guava 版本校验和错误。我尝试重新安装它，问题仍然存在。两次安装时，我都使用 linux 存档管理器(这是我的网络浏览器中的默认行为)打开 .jar 文件并将其保存到磁盘。我又试了一次，这次使用 wget 下载 .jar 文件，问题就解决了。所以这个故事的寓意似乎是:不要使用 linux 归档管理器将 .jar 文件保存到磁盘。