写好一个java代码，除了需要严谨的思维逻辑之外，还需要积累一些代码段，这样在必要的时刻还能给代码锦上添花，那么接下来我们就来给大家分享一些实用的java新手代码必背代码!
1. 字符串有整型的相互转换
String a = String.valueOf(2); //integer to numeric string int i = Integer.parseInt(a); //numeric string to an int
2. 向文件末尾添加内容
BufferedWriter out = null;
try
{
out = new BufferedWriter(new FileWriter(”filename”, true));
out.write(”aString”);
}
catch (IOException e)
{
// error processing code
}
finally
{
if (out != null)
{
out.close();
}
}3. 得到当前方法的名字
String methodName = Thread.currentThread().getStackTrace()[1].getMethodName();
4. 转字符串到日期
java.util.Date = java.text.DateFormat.getDateInstance().parse(date String);
或者是：
SimpleDateFormat format = new SimpleDateFormat( "dd.MM.yyyy" ); Date date = format.parse( myString );
5.把 Java util.Date 转成 sql.Date
java.util.Date utilDate = new java.util.Date(); java.sql.Date sqlDate = new java.sql.Date(utilDate.getTime());
6.把 Array 转换成 Map
import java.util.Map;
import org.apache.commons.lang.ArrayUtils;
public class Main
{
public static void main(String[] args)
{
String[][] countries = {
{
"United States"
, "New York"
}
, {
"United Kingdom"
, "London"
}
, {
"Netherland"
, "Amsterdam"
}
, {
"Japan"
, "Tokyo"
}
, {
"France"
, "Paris"
}
};
Map countryCapitals = ArrayUtils.toMap(countries);
System.out.println("Capital of Japan is " + countryCapitals.get("Japan"));
System.out.println("Capital of France is " + countryCapitals.get("France"));
}
}7.使用JDBC链接Oracle
public class OracleJdbcTest
{
String driverClass = "oracle.jdbc.driver.OracleDriver";
Connection con;
public void init(FileInputStream fs) throws ClassNotFoundException, SQLException, FileNotFoundException, IOException
{
Properties props = new Properties();
props.load(fs);
String url = props.getProperty("db.url");
String userName = props.getProperty("db.user");
String password = props.getProperty("db.password");
Class.forName(driverClass);
con = DriverManager.getConnection(url, userName, password);
}
public void fetch() throws SQLException, IOException
{
PreparedStatement ps = con.prepareStatement("select SYSDATE from dual");
ResultSet rs = ps.executeQuery();
while (rs.next())
{
// do the thing you do
}
rs.close();
ps.close();
}
public static void main(String[] args)
{
OracleJdbcTest test = new OracleJdbcTest();
test.init();
test.fetch();
}
}掌握好这些代码段，可以更加方便程序员的开发，也能为开发人员节省时间，所以平时积累一些代码是很有必要的!最后大家如果想要了解更多java入门知识，敬请关注奇Q工具网。
推荐阅读：