关于从jtabl中取数，跪求答案啊

int row=-1;
for(int i=0;i<v.length;i++){
for(int j=0;j<v[i].length;j++){
for(int k=0;k<v[i][j].length;k++){
for(int l=0;l<v[i][j][k].length;l++){
//v[i][j][k][l]=new Variable();
v[i][j][k][l]=new Variable();
row++;
v[i][j][k][l].setTheta(Double.parseDouble((String)tableModel.getValueAt(row, 0)));
v[i][j][k][l].setTal(Double.parseDouble((String)tableModel.getValueAt(row, 1)));
v[i][j][k][l].setDegreeOfMembership(Double.parseDouble((String)tableModel.getValueAt(row, 2)));
v[i][j][k][l].setNonDegreeOfMembership(Double.parseDouble((String)tableModel.getValueAt(row, 3)));
}
}
}
}

            求大家看一下为什么报空指针异常，我想从jtable中取数然后放到对象中

看下是哪一行报错，像强制类型转换，字符串转数字，模型取值这些都可能出错。