小编Joe*_*ark的帖子

每次我尝试构建我的c ++文件时都会收到此错误

"/usr/bin/make" -f nbproject/Makefile-Debug.mk QMAKE= SUBPROJECTS= .build-conf
make[1]: Entering directory `/c/Users/Joey/Documents/NetBeansProjects/C++Train'
"/usr/bin/make"  -f nbproject/Makefile-Debug.mk dist/Debug/MinGW-Windows/c__train.exe
make[2]: Entering directory `/c/Users/Joey/Documents/NetBeansProjects/C++Train'
make[2]: mkdir: Command not found
mkdir -p build/Debug/MinGW-Windows
make[2]: Leaving directory `/c/Users/Joey/Documents/NetBeansProjects/C++Train'
make[1]: Leaving directory `/c/Users/Joey/Documents/NetBeansProjects/C++Train'
make[2]: *** [build/Debug/MinGW-Windows/HelloWorld.o] Error 127
make[1]: *** [.build-conf] Error 2
make: *** [.build-impl] Error 2


BUILD FAILED (exit value 2, total time: 2s)

我检查了make.exe所在的目录,mkdir就在那里,所以我只是感到困惑.

我的代码本身没有显示错误:

#include <iostream>

int main() {
    using namespace std;
    cout << "Hello World!" << endl;
    return 0;
}

只是一个简单的小世界来测试netbeans.

作为java swing GUI界面和我在学校即将推出的Geometry课程的介绍,我决定为该课程制作一个"特殊"计算器.现在我有一个空指针,我不太明白是什么导致它.我编程的方式适用于我的其他课程,为什么它不能在这里工作？

无论如何这里是错误所在的两个类,另外两个有效,我不明白我做了什么不同.这是错误:

Exception in thread "AWT-EventQueue-0" java.lang.ExceptionInInitializerError
    at geohelper.GeoFrame.addToGUI(GeoFrame.java:90)
    at geohelper.GeoFrame.showGUI(GeoFrame.java:42)
    at geohelper.GeoHelper$1.run(GeoHelper.java:13)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:727)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:688)
    at java.awt.EventQueue$3.run(EventQueue.java:686)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:697)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
Caused by: java.lang.NullPointerException
    at geohelper.RPrismListener.<init>(RPrismListener.java:21)
    at geohelper.RecPrism.<clinit>(RecPrism.java:14)
    ... 17 more

这是形状的类(矩形棱镜)

package geohelper;

import java.awt.Container;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.event.DocumentListener;

public class RecPrism {

    static final JButton rprismbutton = new JButton("Calculate");
    static final JTextField rplength …