使用If...Else减少嵌套的一种方式

public class IfElseTest {

    public static void main(String[] args) {

        String num = "123456789";

        if (num.isEmpty()) {
            System.out.println("数字为空");
        } else {
            if (num.startsWith("0")) {
                System.out.println("开头数字为0");
            } else {
                if (num.charAt(1) == 0) {
                    System.out.println("第二位数字为0");
                } else {
                    if (num.length() == 3) {
                        System.out.println("长度为3");
                    } else {
                        if (num.contains("425")) {
                            System.out.println("字符串里面有425");
                        } else {
                            if (num.equals("122714554")) {
                                System.out.println("字符串和122714554相同");
                            } else {
                                if (num.endsWith("5")) {
                                    System.out.println("字符串最后一位是5");
                                } else {
                                    System.out.println(num);
                                }
                            }
                        }
                    }
                }
            }
        }

        System.out.println("********************************");

        if (num.isEmpty()) {
            System.out.println("数字为空");
            return;
        }

        if (num.startsWith("0")) {
            System.out.println("开头数字为0");
            return;
        }

        if (num.charAt(1) == 0) {
            System.out.println("第二位数字为0");
            return;
        }
        if (num.length() == 3) {
            System.out.println("长度为3");
            return;
        }

        if (num.contains("425")) {
            System.out.println("字符串里面有425");
            return;
        }

        if (num.equals("122714554")) {
            System.out.println("字符串和122714554相同");
            return;
        }

        if (num.endsWith("5")) {
            System.out.println("字符串最后一位是5");
            return;
        }

        System.out.println(num);

    }

}