NameError：未定义名称“ sys”

Question

如何解决此错误，请先在此处发布

public static void main(String[] args) {
    // TODO Auto-generated method stub
    launch(args);
}
public void start(Stage primaryStage) throws Exception{
    Double[][] A = new Double[6][6];
    Label tamanoML = new Label("Tamaño Matriz:");
    Spinner tamanoMS =new Spinner(1,5,0,1);
    int tamano=(int) tamanoMS.getValue();
    int r;
    Label[] campoL = new Label[6];  
    TextField campo [][] = new TextField[6][6];

    Button resolverB = new Button("Resolver matrix");
    resolverB.setOnAction((ActionEvent t) -> {
        int n=(int) tamanoMS.getValue();
        int cont=0;
        for(int i=0; i<n; i++) {
            for(int j=0; j<n+1; j++) {
                A[i][j]=Double.parseDouble(campo[i][j].getText());
            }
        }
        for (int a = 0; a < n; a++) {
            Double temp = 0.0;
            temp = A[cont][cont];
            for (int y = 0; y < (n + 1); y++) {
                A[cont][y] = A[cont][y] / temp;
            }

            for (int x = 0; x < n; x++) {
                if (x!=cont) {
                    Double c = A[x][cont];
                    for (int z = 0; z < (n + 1); z++) {
                        A[x][z] = ((-1 * c) * A[cont][z]) + A[x][z];
                    }
                }
            }
            cont++;
        }
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n+1; j++) {
                campo[i][j].setText(""+A[i][j]);
            }
        }
    });
    Button limpiarb = new Button("Limpiar");
    limpiarb.setOnAction((ActionEvent t) -> {
        for(int i=0; i<tamano+1; i++) {
             for(int j=0; j<tamano+1; j++) {
                campo[i][j].setText("0"); 

             }
        }
    }); 

    GridPane mainPane = new GridPane();
    mainPane.setMinSize(650,350); 
    mainPane.setPadding(new Insets(10,10,10,10)); 
    mainPane.setVgap(5); 
    mainPane.setHgap(5);       
    mainPane.setAlignment(Pos.CENTER); 


    mainPane.add(tamanoML, 0, 0); 
    mainPane.add(tamanoMS, 1, 0);
    mainPane.add(resolverB,0,1); 
    mainPane.add(limpiarb,1,1);
    for(int i=0; i<tamano+1; i++) {
        r=i+1;
            if(r<tamano+1) {
                r=i+1;
                campoL[i]=new Label("X"+r);
                mainPane.add(campoL[i],i,2);
            }else {
                campoL[i]=new Label("R");
                mainPane.add(campoL[i],i,2);
            }
    }
    for(int i=0; i<tamano; i++) {
        for(int j=0; j<tamano+1; j++) {
            campo[i][j] = new TextField("0");
            mainPane.add(campo[i][j],j,i+3);
        }
    }
    tamanoMS.valueProperty().addListener((newValue) ->  {
        int s;
        for(int i=0; i<tamano+1; i++) {
            s=i+1;
                if(s<tamano+1) {
                    s=i+1;
                    campoL[i]=new Label("X"+s);
                    mainPane.add(campoL[i],i,2);
                }else {
                    campoL[i]=new Label("R");
                    mainPane.add(campoL[i],i,2);
                }
        }
        for(int i=0; i<tamano; i++) {
            for(int j=0; j<tamano+1; j++) {
                campo[i][j] = new TextField("0");
                mainPane.add(campo[i][j],j,i+3);
            }
        }
        s=0;
    });
    Scene scene = new Scene(mainPane); 

    primaryStage.setScene(scene);

    primaryStage.setTitle("Ventas del Dia");

    primaryStage.show();
}

代码如下所示：

Traceback (most recent call last):
  File "check.py", line 22, in <module>
    exc(db,cur,sql)
  File "/home/ssnaseem/explanations/explanations/Code/Explainatoin tables postgres/explanationTables/helpers.py", line 39, in exc
    print(sys.exc_info())
NameError: global name 'sys' is not defined