如何解决线程“ main” java.lang.NullPointerException中的异常问题？

Question

我正在尝试执行程序的主类，但遇到有关NullPointerException的错误，导致错误的方法如下

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我收到如下错误
线程“主”中的异常java.lang.NullPointerException     在CCA.Main.main（Main.java:361） 361行是

public double fitness(List<Double> position) {
        double newFitness=0;
      double[] features = NewMath.Position2Features(position_new);
        Dataset[] foldsTem = new Dataset[problem.getNumFolds()];
        for (int f = 0; f < problem.getNumFolds(); f++) {
            foldsTem[f] = HelpDataset.removeFeatures(problem.getFoldsTrain()[f].copy(), features);
        }
        double accuracy = 0.0;//
        for (int f = 0; f < problem.getNumFolds(); f++) { //10 fold cross validation
            Dataset testTem = foldsTem[f];
            Dataset trainTem = new DefaultDataset();
            for (int j = 0; j < problem.getNumFolds(); j++) {
                if (j != f) {
                    trainTem.addAll(foldsTem[j]);
                }
            }
            accuracy += problem.getMyclassifier().classify(trainTem, testTem);
        }
        double error = 1.0 - accuracy / (double) problem.getNumFolds();
        int size = HelpDataset.sizeSubset(features);
        newFitness =  0.5* accuracy + 0.5 * ( (size) / (double) problem.getTraining().noAttributes());
        return newFitness; 
    }

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