java练习程序1
/*import javax.swing.JFrame;*/
/*import javax.swing.JOptionPane;*/
public class TestFrame{
public static void main(String[] args) throws Exception{
/*JFrame frame1 = new JFrame();
frame1.setTitle("Windows 1");
frame1.setSize(200,150);
frame1.setLocation(200,100);
frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame1.setVisible(true);
JFrame rx = new JFrame();
rx.setTitle("rx's Windows");
rx.setSize(300,300);
rx.setLocation(0,0);
rx.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
rx.setVisible(true);*/
/*String s = "Welcome to java";
String s1 = new String("Welcome to java");
String s2 = s1.intern();
String s3 = "Welcome to java";
System.out.println("s1 == s is" + (s1 == s));
System.out.println("s2 == s is" + (s2 == s));
System.out.println("s.intern() == s3.intern() is" + (s.intern() == s3.intern()));
String s4 = "Welcome";
String s5 = "j a v a";
System.out.println();
System.out.println(s4.toLowerCase());
System.out.println(s4.toUpperCase());
System.out.println(s5.trim());
System.out.println(s4.replace('e','A'));
System.out.println(s4.replaceAll("e","E"));*/
/*System.out.println("Welcome to java".indexOf('W'));
System.out.println("Welcome to java".indexOf('o'));
System.out.println("Welcome to java".indexOf('o',5));
System.out.println("Welcome to java".indexOf("come"));
System.out.println("Welcome to java".indexOf("java",5));
System.out.println("Welcome to java".indexOf("Java",5));
System.out.println("Welcome to java".lastIndexOf('W'));
System.out.println("Welcome to java".lastIndexOf('o'));
System.out.println("Welcome to java".lastIndexOf('o',5));
System.out.println("Welcome to java".lastIndexOf("come"));
System.out.println("Welcome to java".lastIndexOf("java",5));
System.out.println("Welcome to java".lastIndexOf("Java",5));*/
/*char[] chars = "Java".toCharArray();
getChars(int srcBegin,int
相关文档：
手动建表：
CREATE TABLE `excel` (
`id` int(11) DEFAULT NULL,
`name` varchar(50) DEFAULT NULL,
`passwd` varchar(50) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=gb2312; 注意是gb2312
然后在连接数据库时加上:
useUnicode=true&characterEncoding=gb2312.
就ok啦！ ......
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();
Object val = entry.getValue();
}
效率高,以后一定要使用此种方式！
第二种:
Map map = new HashMap();
Iterato ......
fm.split("["); // error
-------------------
java.util.regex.PatternSyntaxException: Unclosed character class near index 0[+
^
at java.util.regex.Pattern.error(Unknown Source)
at java.util.regex.Pattern.clazz(Unknown Source)
& ......
对于初学者，也行大家会认为Java包含JavaScript，然而这种从字面意思的理解是错误的，下面小编浅谈一下JavaScript与java的区别。
1. 基于对象和面向对象
Java是一种真正的面向对象的语言，即使是开发简单的程序，必须设计对象。
JavaScript是种脚本语言，它可以用来制作与网络无关的，与用户交互作用的复杂软件。 ......
//1.编写一个程序，该程序可读入一个外部文件，并将文件内容赋值给一个字符串
package Zhangyiwei
import java.io.*;
public class Zhangyiwei {
public static String filename = "c:\\1.txt";
public static void main(String[] args) throws FileNotFoundException, IO ......
