java7新特性

package com.test;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * 
 * @author 测试java7的新特性
 */
public class TestJava7
{
    // 1. 支持二进制字面值
    public static void binaryLiteral()
    {
        int a = 0b100;
        int b = 0B1100;
        int c = a & b;
        System.out.println(c);
    }

    // 2. 数字字面值中添加下划线"_"分割
    public static void underlineInNumber()
    {
        /*
         * <注意: 数字的开头结尾不能添加; 小数点前后不能添加; F或L前面不能添加>
         */
        int a = 1_2_3;
        long b = 92_3L;
        double c = 3.14_15926;
        double d = 3.1_415F;
        System.out.println(a);
        System.out.println(b);
        System.out.println(c);
        System.out.println(d);
    }

    // 3. switch表达式支持string常量
    public static void switchSupportString()
    {
        String str = "ccc";
        switch (str)
        {
        case "aaa":
            System.out.println("I'm first");
            break;
        case "bbb":
            System.out.println("I'm second");
            break;
        case "ccc":
            System.out.println("I'm third");
            break;
        default:
            System.out.println("not matched");
            break;
        }
    }

    //4. try-with-resources特性支持自动关闭实现了java.lang.AutoCloseable和java.io.Closeable接口的对象资源
    // 一个 try-with-resources 语句可以像普通的 try 语句那样有 catch 和 finally 块。
    // 在try-with-resources 语句中, 任意的 catch 或者 finally 块都是在声明的资源被关闭以后才运行
    public static void tryWithResources()
    {
        try
        {
            Class.forName("com.mysql.jdbc.Driver");
            // 将对象声明在try()中
            try (Connection connection = DriverManager.getConnection(
                    "jdbc:mysql://172.17.13.38:3306/g2mdev", "root", "");

                    PreparedStatement preparedStatement = connection
                            .prepareStatement("select SQL_CALC_FOUND_ROWS * from g2m_sec_account where id = ? or id = ? or id = ?");)
            {
                preparedStatement.setString(1, "1");
                preparedStatement.setString(2, "2");
                preparedStatement.setString(3, "3");

                try (ResultSet resultSet = preparedStatement.executeQuery())
                {
                    ResultSetMetaData meta = resultSet.getMetaData();
                    for (int i = 0; i < meta.getColumnCount(); ++i)
                    {
                        System.out.printf("%20s  ", meta.getColumnName(i + 1));
                    }
                    System.out.println();
                    while (resultSet.next())
                    {
                        for (int i = 0; i < meta.getColumnCount(); ++i)
                        {
                            System.out.printf("%20s  ", resultSet
                                    .getString(meta.getColumnName(i + 1)));
                        }
                        System.out.println();
                    }
                }
            }
            catch (SQLException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        catch (ClassNotFoundException e)
        {
            e.printStackTrace();
        }
    }

    //5. 一个catch块捕获多个异常
    public static void multiCatch()
    {
        BufferedReader bufferedReader;
        try
        {
            bufferedReader = new BufferedReader(new FileReader(
                    "d:/note.txt"));
            String buffer = null;
            while (null != (buffer = bufferedReader.readLine()))
            {
                System.out.println(buffer);
            }
            bufferedReader.close();
            throw new MyException("-------ERROR-------"); 
        }
        catch (IOException | MyException e)
        {
            e.printStackTrace();
        }
    }
    
    //6. 创建泛型对象时类型推断
    public static void genericTypeInfer()
    {
        List<String> list = new ArrayList<>();
        list.add("aaa");
        list.add("bbb");
    }
    public static void main(String[] args)
    {
        binaryLiteral();
        System.out.println("-------------");
        underlineInNumber();
        System.out.println("-------------");
        switchSupportString();
        System.out.println("-------------");
        tryWithResources();
        System.out.println("-------------");
    }
}
class MyException extends Exception
{
    private static final long serialVersionUID = 884387500985353045L;

    public MyException(String string)
    {
        super(string);
    }
}