JAVA实现随机四则运算

if(judge(num)){
            
            char[] operator = new char[]{‘+‘,‘-‘,‘*‘,‘/‘};
            Random random = new Random();
            ArrayList expression = new ArrayList();
            for(int i=0 ; i){
                
                int n = random.nextInt(3) + 3;//3-5个运算符
                int[] number = new int[n+1];
                String ex = new String();
                for(int j=0 ; j){
                    
                    number[j] = random.nextInt(100) + 1;//4-6个数字
                    
                }
                for(int j=0 ; j){
                    
                    int s = random.nextInt(4);//随机选择某个运算符
                    ex += String.valueOf(number[j]) + String.valueOf(operator[s]);
                    if(s==3){
                        
                        number[j+1] = decide(number[j],number[j+1]);
                        
                    }
                    
                }
                ex += String.valueOf(number[n]);
                expression.add(ex);
                
            }

    /**
     * 计算每个等式的结果，并返回运算式
     */
    static ScriptEngine jse = new ScriptEngineManager().getEngineByName("JavaScript");
    private static ArrayList calculate(ArrayList arrayList){
        ArrayList ArithExpress=new ArrayList();
        for(String ax:arrayList){
            try {
                ax=ax+"="+jse.eval(ax);
                System.out.println(ax);
                ArithExpress.add(ax);
            } catch (ScriptException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return ArithExpress;
    }
    
    private static boolean judge(int data){
        if(data>=0){
            int temp=(int)data;
            if(temp==data)
                return true;
            else
                return false;
        }
        else{
            return false;
        }
}