corpse2010的专栏

class Person6{String name ;int age ;}public class TestRefDemo1{public static void main(String[] args){// 声明一对象 p1，此对象的值为 null，表示未实例化Person6 p1 = null ;// 声明一对象 p2，此对象的值为 null，表示未

class Person01{String name ;int age ;Person01(String name,int age){this.name = name ;this.age = age ;}boolean compare(Person01 p){if(this.name.equals(p.name)&&this.age==p.age){

JDK（Java Development Kit）是整个Java的核心，包括了Java运行环境、Java工具和Java基础类库。JDK作为JAVA开发的环境，不管是做JAVA开发还是做安卓开发，都必须在电脑上安装JDK。在安装完jdk后，还需要对jdk的环境变量进行配置才能正常使用，下面教大家如何配置jdk环境变量：1.右键选择 计算机→属性→高级系统设置→高级→环境变量

How to Check an HashMap is Empty or not import java.util.HashMap;import java.util.Map;/** * This example is used to show * 1) How to Check an HashMap is Empty or

第一种: Map map = new HashMap(); Iterator iter = map.entrySet().iterator(); while (iter.hasNext()) {     Map.Entry entry = (Map.Entry) iter.next();     Object key = entry.getKey();     Ob

class Person00{private String name ;private int age ;public Person00(String name,int age){this.name = name ;this.age = age ;}public String talk(){return "我是："+name+"，今年："+age+"岁"

问题描述：  在java语言中，map的clear方法会把整个map清空吗？问题解答：  答案是肯定的测试代码：    HashMap hashMap = new HashMap();    hashMap.put("1", "mqboss");    hashMap.put("2", "Jboss");    System.out.println("hashMap

String test = "OAS lesson nine";boolean result1 = test.contains("OAS");boolean result2 = test.contains("lesson");boolean result3 = test.contains("NINE");boolean result4 = test.contains("oas le

public class TestEquals1 {public static void main(String[] args) {// TODO Auto-generated method stub       String str1 = new String("java") ;       String str2 = new String("java") ;   

class Person05{String name ;int age ;private static String city = "中国";public Person05(String name,int age){this.name = name ;this.age = age ;}public String talk(){return "

class Change{int x = 0 ;}public class TestRefDemo2 {public static void main(String[] args) {// TODO Auto-generated method stubChange c = new Change() ;c.x = 20 ;fun(c)

public class TestPersonDemo2 {public static void main(String[] args) {// TODO Auto-generated method stubPerson p = new Person() ;// 给 p 中的属性赋值p.name = "张三" ;// 在这里将对象 p 的年龄属性赋值为-25 岁

class Person5{ private String name ; private int age ; private void talk()   //The method talk() from the type Person1 is not visible  {  System.out.println("我是："+name+"，今年："+age+"岁"); 

class Person7{ public Person7()// Person 类的构造方法 {System.out.println("public Person()") ;}}public class TestConstruct {public static void main(String[] args) {// TODO Auto

class Person8{private String name ;private int age ;public Person8(String n,int a){name = n ;age = a ;System.out.println("public Person(String n,int a)") ;}public String talk(){

class Person9{  private String name ;  private int age ;  public Person9()  {}  public Person9(String n,int a)  {     name = n ;  }  public String talk() {    return "我是："+na

public class TestEquals {public static void main(String[] args) {// TODO Auto-generated method stub  String str1 = new String("java") ;      String str2 = new String("java") ;      Strin

class Person03 {     String name ;        int age ;     String city ;     public Person03(String name, int age, String city)     {        this.name = name ;        this.city = city ;

1、方法介绍（1）indexOf(int ch) 返回指定字符在此字符串中第一次出现处的索引（2）indexOf(String str) 返回指定子字符串在此字符串中第一次出现处的索引（3）indexOf(int ch, int fromIndex) 返回在此字符串中第一次出现指定字符处的索引，从指定的索引开始搜索（4）indexOf(String str, int