publicclassUser{privateStringusername;publicvoidsetUsername(Stringusername){check(username!=null,"用户名不能为空");check(username.length()>=6&&username.length()<=20,"用户名长度应在6-20之间");this.username=username;}// 其他代码...} 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 在上述示例...
* StringCheckUtil.isEmpty(" ") = true * StringCheckUtil.isEmpty("bob") = flase * StringCheckUtil.isEmpty(" bob ") = flase *@returnboolean 空则返回true,非空则flase*/publicstaticbooleanisEmpty(String input) {returnnull== input || 0 == input.length() || 0 == input.replaceAll("\\...
public void copy(String[] a, String[] b, String ending) { int index; String temp = null; //空指针错误 System.out.println(temp.length()); //未使用变量 int length=a.length; for(index=0; index&a.length; index++) { //多余的if语句 if(true) { //对象比较 应使用equals if(temp==e...
static boolean checkForRotation(String str1, String str2) { // Check if both strings have the same length and str2 is found in the concatenated str1+str1. return (str1.length() == str2.length()) && ((str1 + str1).indexOf(str2) != -1); } // Main method to execute the p...
Java: Check if String is Numeric How to Convert String to int in Java Reverse a String in Java Convert int to String in Java How to Split a String in Java: Different Examples Convert Char to String in Java Java String Methods Every Developer Should Know ...
Below is the Java program to check for digits and other characters ?Open Compiler public class Demo { public static void main(String []args) { String str = "5demo9"; System.out.println("String: "+str); if(str.matches("[0-9]+") && str.length() > 2) { System.out.println("...
publicclassSimpleTesting{publicstaticvoidmain(String[]args){String str="1123";booleanisNumeric=true;for(inti=0;i<str.length();i++){if(!Character.isDigit(str.charAt(i))){isNumeric=false;}}System.out.println(isNumeric);}} Output:
在某个JavaBean中,我们可以使用该注解: public class Person { @Range(min=1, max=20) public String name; @Range(max=10) public String city; } 1 2 3 4 5 6 7 但是,定义了注解,本身对程序逻辑没有任何影响。我们必须自己编写代码来使用注解。这里,我们编写一个Person实例的检查方法,它可以检查Perso...
同时,由于Null属于String类型,因此在编译如下代码段时,Java甚至都不会有任何警告。 但是,我们一旦运行该程序代码,就会出现失败,并且会被提示如下的空指针异常: 空指针异常的定义 空指针异常属于运行时的异常。当Java尝试去调用真实对象上的任何方法时,如果在运行时中,该对象调用的是空引用(Null Reference),那么就会抛...
3. Using Core Java Let’s now see how we can perform the same check if we don’t want to use regular expressions. We’ll take advantage ofCharacterandStringclasses and their methods to check if all required characters are present in ourString: ...