Java实现-每天三道剑指Offre(2-4)

 1 /**
 2  * 面试题2：实现单例模式
 3  * 
 4  * @author qiuyong 饿汉式
 5  */
 6 public class Singleton01 {
 7     private Singleton01() {
 8     }
 9 
10     private static Singleton01 instance = new Singleton01();
11 
12     public static Singleton01 getInstance() {
13         return instance;
14     
15     }
16 }
17 
18 /**
19  * 面试题2:懒汉式
20  * @author qiuyong
21  */
22 public class Singleton02 {
23     
24     public static Singleton02 instance;
25     
26     public synchronized static Singleton02 getInstance(){
27         if(null==instance){
28             instance=new Singleton02();
29         }        
30         return instance;
31     }
32 
33 }
34 
35 /**
36  * 面试题2:利用内部类
37  * @author qiuyong
38  */
39 public class Singleton03 {
40     
41     public static Singleton03 getInstance(){
42         return  InnerClass.instatnce;
43     }
44     
45     private static class InnerClass{
46         public static Singleton03 instatnce=new Singleton03();
47     }
48 }

public class Test {
    public static boolean find(int [][] arry,int num){
        int column=arry[0].length-1;
        int row=0;
        while(row<arry.length&&column>=0){
            if(num==arry[row][column]){
                return true;
            }
            if(arry[row][column]>num){
                column--;
            }else{
                row++;
            }
            
        }
        return false;
    }
    
    public static void main(String[] args) {
        int [][] arry=new int[3][3];
        for(int i=0;i<arry.length;i++){
            for(int j=0;j<arry[0].length;j++){
                arry[i][j]=(i+1)*(j+1);
            }
        }
        
        System.out.println("查看是否有元素9:"+find(arry,9));
        System.out.println("查看是否有元素9:"+find(arry,0));
    }

}

 1 public class ReplaceBlank {
 2     public static void main(String[] args) {
 3         String str="i am happy";
 4         str=replaceBlank(str);
 5         System.out.println(str);
 6     }
 7     
 8     
 9     public static String replaceBlank(String str){
10         if(null==str){
11             return null;
12         }
13         StringBuffer sb=new StringBuffer();
14         for(int i=0;i<str.length();i++){
15             if(str.charAt(i)==‘ ‘){
16                 sb.append("%20");
17             }else{
18                 sb.append(str.charAt(i));
19             }
20         }
21         return sb.toString();
22     }
23 
24 }