jdk7 新特性测试-1 -（demo来源于网上）

package jdk7;

import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class Jdk7Test {

public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
System.out.println(switchString("Monday"));

//抛出异常
catchTest();
}

//Switch语句支持string类型
public static String switchString(String dayOfWeekArg){
String typeOfDay;
        switch (dayOfWeekArg) {
            case "Monday":
                typeOfDay = "Start of work week";
                break;
            case "Tuesday":
            case "Wednesday":
            case "Thursday":
                typeOfDay = "Midweek";
                break;
            case "Friday":
                typeOfDay = "End of work week";
                break;
            case "Saturday":
            case "Sunday":
                typeOfDay = "Weekend";
                break;
            default:
                throw new IllegalArgumentException("Invalid day of the week: " + dayOfWeekArg);
        }
        return typeOfDay;
}

//1.4 catch
public static void catchTest( ) throws Exception {
String zipFileName = "";
try {
    System.out.println("error");
    if(true){
    throw new IOException();
    }else{
    throw new SQLException();
    }
} catch (IOException|SQLException ex) {
    throw ex;
}
}

//1.6 泛型实例的创建可以通过类型推断来简化可以去掉后面new部分的泛型类型，只用<>就可以了
public static void listTest( ) throws Exception {
List<String> list = new ArrayList<>();
list.add("A");
}

}

fork-join

package jdk7;

import java.util.Date;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.Future;
import java.util.concurrent.RecursiveTask;

//最大的增强，充分利用多核特性，将大问题分解成各个子问题，
//由多个cpu可以同时解决多个子问题，最后合并结果，继承RecursiveTask，
//实现compute方法，然后调用fork计算，最后用join合并结果

//算法很简单，在100个数以内的我们直接迭代计算和值。否则采用Fork/Join框架分治计算。
public class PlusPlus extends RecursiveTask<Long>{
    private static final int THRESHOLE=100;
    private int start;
    private int end;
    public PlusPlus(int start,int end){
        this.start=start;
        this.end=end;
    }

    @Override
    protected Long compute() {
        // TODO Auto-generated method stub
    Long sum=0l;
        if(end-start<THRESHOLE){
            for(int i=start;i<=end;i++){
                sum+=i;
            }
        }else{
            int middle=(start+end)/2;
            PlusPlus left=new PlusPlus(start, middle);
            PlusPlus right=new PlusPlus(middle+1, end);

            left.fork();
            right.fork();
            sum=left.join()+right.join();
        }
        return sum;
    }

    public Long sumall(){
    long sum=0;
    for(int i=start;i<=end;i++){
    sum = sum+ i;
    }
    return sum;
    }

    public static void main(String args[]) throws InterruptedException, ExecutionException{
    long t1 = new Date().getTime();

        ForkJoinPool pool=new ForkJoinPool();
        Future<Long> result=pool.submit(new PlusPlus(1, 800000));

        long t2 = new Date().getTime();
        long sum = new PlusPlus(1, 800000).sumall();
        long t3 = new Date().getTime();
        System.out.println(result.get()+"耗时:"+(t2-t1));
        System.out.println(sum+"耗时:"+(t3-t2));
//        System.err.println(10001*5000);
    }

}

320000400000耗时:2
320000400000耗时:3

注：
使用fork 有个局限   800000 变成 1000000时候出现 OutOfMemory
而后面一种方式就不会出现这个错误

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jdk7 新特性测试-1 -（demo来源于网上）

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