java随记

随机数：UUID.randomUUID().hashCode()

在项目中用来全局缓存信息：

import java.util.HashMap;
import java.util.Map;

import com.jusfoun.core.main.etl.bean.KettleJob;

public class JavaMapCache {

	private static Map<String , KettleJob> mapCache = null;
	private JavaMapCache(){
		
	}
	static {
		mapCache = new HashMap<>();
		//这里查询数据库，保存map中
	}
	
	public static void putValue(String name, KettleJob obj){
		mapCache.put(name, obj);
	}
	
	public static KettleJob getValue(String name){
		return mapCache.get(name);
	}
	
	public static void removeValue(String name){
		mapCache.remove(name);
	}
	
	//用于清除缓存信息
	 public static void clearCache() {
		 mapCache.clear();
	 }
	 
	

	public static Map<String, KettleJob> getMapCache() {
		return mapCache;
	}

	
}

2、list转化成数组：

<pre name="code" class="java">public class Test {  
    public static void main(String[] args) {  
        List<String> list=new ArrayList<String>();  
        list.add("王利虎");  
        list.add("张三");  
        list.add("李四");  
        int size=list.size();  
        String[] array = (String[])list.toArray(new String[size]);  
        for(int i=0;i<array.length;i++){  
            System.out.println(array[i]);  
        }  
    }  
}