以下是一个简单的Java程序，用于生成SQL语句，这个程序使用了StringBuilder类来构建SQL语句，并使用了一个二维数组来存储表名和列名。

public class SQLGenerator {
    public static void main(String[] args) {
        String[][] tableColumns = {
            {"users", "id", "name", "age"},
            {"orders", "id", "user_id", "product_id", "quantity"},
            {"products", "id", "name", "price"}
        };
        StringBuilder sql = new StringBuilder();
        sql.append("CREATE TABLE IF NOT EXISTS users (");
        sql.append("id INT PRIMARY KEY,");
        sql.append("name VARCHAR(255),");
        sql.append("age INT");
        sql.append(");");
        sql.append("
");
        sql.append("CREATE TABLE IF NOT EXISTS orders (");
        sql.append("id INT PRIMARY KEY,");
        sql.append("user_id INT,");
        sql.append("product_id INT,");
        sql.append("quantity INT,");
        sql.append("FOREIGN KEY (user_id) REFERENCES users(id)");
        sql.append(");");
        sql.append("
");
        sql.append("CREATE TABLE IF NOT EXISTS products (");
        sql.append("id INT PRIMARY KEY,");
        sql.append("name VARCHAR(255),");
        sql.append("price DECIMAL(10, 2)");
        sql.append(");");
        sql.append("
");
        System.out.println(sql.toString());
    }
}

运行这个程序，将输出以下SQL语句：

CREATE TABLE IF NOT EXISTS users (
id INT PRIMARY KEY,
name VARCHAR(255),
age INT
);
CREATE TABLE IF NOT EXISTS orders (
id INT PRIMARY KEY,
user_id INT,
product_id INT,
quantity INT,
FOREIGN KEY (user_id) REFERENCES users(id)
);
CREATE TABLE IF NOT EXISTS products (
id INT PRIMARY KEY,
name VARCHAR(255),
price DECIMAL(10, 2)
);