Java从一个多数组中选择一个随机项而不过度使用它?

    private String[][] questions = 
    {
        {"Sky's color is black", "false"},
        {"The earth is round.", "true"}, 
        {"Google is written in PHP", "false"},
        {"This program is written in JAVA", "true"}, 
        {"Daniel is white", "true"}
    };

    public void selectRandomQuestion() {

    }
    private String[][] questions = 
    {