無法創建JexlEngine對象

我寫了下面的類：無法創建JexlEngine對象

import org.apache.commons.jexl2.*; 

public class NelderMead { 
    // контсанты 
    private static int  M = 3; 
    private static double E = 0.005; 
    private static double A = 1.000; 
    private static double B = 0.500; 
    private static double Y = 2.000; 

    // переменные 
    private JexlEngine jexl = new JexlEngine(); 
    private Expression func; 
    private String funcString = ""; 
    private MapContext[] iterations; 

    public NelderMead(){ 
     this.jexl = new JexlEngine(); 
    } 

    public NelderMead(String funcString){ 
     this.jexl = new JexlEngine(); 
     this.setFunc(funcString); 
    } 


    public void setFunc(String funcString){ 
     this.funcString = funcString; 
     this.func = this.jexl.createExpression(funcString); 
    } 

    public double funcEval(MapContext args){ 
     return (Double) this.func.evaluate(args); 
    } 

    public boolean checkCriterian(){ 
     return true; 
    } 
}

但我創建這個類我有foolowing錯誤的對象：

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory 
    at org.apache.commons.jexl2.JexlEngine$UberspectHolder.<clinit>(JexlEngine.java:121) 
    at org.apache.commons.jexl2.JexlEngine.getUberspect(JexlEngine.java:205) 
    at org.apache.commons.jexl2.JexlEngine.<init>(JexlEngine.java:182) 
    at org.apache.commons.jexl2.JexlEngine.<init>(JexlEngine.java:170) 
    at NelderMead.<init>(NelderMead.java:22) 
    at Test.main(Test.java:10) 
Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory 
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190) 
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306) 
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) 
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247) 
    ... 6 more

在構造函數的第一行（當創建JexlEngine的對象）：

public NelderMead(String funcString){ 
    this.jexl = new JexlEngine(); 
    this.setFunc(funcString); 
}

能不能幫我 - 爲什麼這個代碼導致錯誤？

PS 我使用.jar文件來使用這個庫。

來源

2011-11-26 dizpers

您需要在運行時在類路徑中提供commons-logging jar

來源

2011-11-26 11:55:36

thx！這對我很好！ – dizpers

不客氣 –

無法創建JexlEngine對象

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