javaの13日間の文字列StringBuffer（二）

StringBufferとStringBuider

/**
 * StringBuffer           
 *   :
 * 1.       
 * 2.            
 * 3.     toString       
 * 
 * 
 * 1.  
 * 		StringBuffer append():                   .
 *      StringBuffer insert(index,  );           index  .
 * 2.  
 *     StringBuffer delete(int start,int end):    start     end
 *     StringBuffer deleteCharAt(int index):        
 * 3.  
 *     StringBuffer replace(int start,int end,String str);
 *     void setCharAt(int index,char c);
 * 4.  
 *    char  charAt(index):          
 *    int indexOf(String str)
 *    int lastIndexOf(String str)
 *    int length()
 *    String subString(int start)
 *    
 * 5.  
 *   StringBuffer reverse();
 *   
 * 6.  
 *  void getChars(int srcBegin,int srcEnd,char[] dst,int dstBegin)  
 *
 *
 *
 *JDK1.5        StringBuilder.
 *
 *	StringBuffer      .
 *	StringBuilder       .                         StringBuilder
 *
 *JDK         
 *  1.    
 *  2.    
 *  3.     
 *
 */
public class StringBufferDemo {
	public static void sop(String str){
		System.out.println(str);
	}
	public static void method_copy(){
		StringBuffer sb=new StringBuffer("abcdef");
		char[] chs=new char[4];
		sb.getChars(0, 4, chs, 0);
		for (char c : chs) {
			sop("getChars"+c);
		}
		
	}
	
	public static void method_update(){
		StringBuffer sb=new StringBuffer("abcdef");
		sb.replace(1, 4, "JAVA");
		sop(sb.toString());
		sb.setCharAt(2,'K');  //          
		sop(sb.toString());
	}
	
	public static void method_delete(){
		StringBuffer sb=new StringBuffer("abcdef");
		sb.delete(1,3);
		sop(sb.toString());
		
		//      
		//sb.delete(0, sb.length());
		
		//   sb   c
		sb.deleteCharAt(2);//    sb.delete(2,3);
		sop(sb.toString());
		
	}
	
	public static void method_create(){
		StringBuffer sb=new StringBuffer();
		StringBuffer sb1=sb.append(34);
		sop("sb==sb1:"+(sb==sb1));
		
		sb.append("sdfsdf").append(true).append(123);
		sop(sb.toString());
	}
	
	public static void main(String[] args) {
		method_create();
		method_delete();
		method_update();
		method_copy();
	}

}

箱に詰めると箱を外す

/**
 *             
 * byte       	Byte
 * short      	short
 * int			Integer
 * boolean 		Boolean
 * float		Float
 * double		Double
 * char			Character
 * 
 *                  
 *   1.                     
 *   
 *             
 *         +"";             
 *          .toString(       );
 *     : Integer.toString(34); // 34        "34"
 *    
 *              . 
 *              .parseXXX(str);
 *     xxx  a=Xxxx.parseXxx(String stt);
 *     
 *     double d=Double.parstDouble("12.13");
 *     
 *          
 * 		toBinaryString();
 *      toHexstrng();
 *      toOctalString();
 * 
 *           
 *    parseInt(string,radix);
 * 
 */


public class IntegerDemo {

	public static void sop(String str){
		System.out.println(str);
	}
	
	public static void main(String[] args) {
		//        
		sop("int max:"+Integer.MAX_VALUE); //                        
		
		
		//           
		int num=Integer.parseInt("123"); //             
		sop("num="+(num+4));
		
		long x=Long.parseLong("123");
		
		
		boolean b=Boolean.parseBoolean("true");
		sop("boolean="+b);
		
		sop(Integer.toBinaryString(6));
		sop(Integer.toHexString(60));
		
		
		int ss =Integer.parseInt("110",10);
		sop(""+ss);
		ss =Integer.parseInt("110",2);
		ss =Integer.parseInt("3c",16);
		sop(""+ss);
		
		Integer i=new Integer("123");
		int sss=i.intValue(); //            
		
		method();
		
		method1();
	}

	public static void method(){
		Integer x=new Integer("123");
		Integer y=new Integer("123");
		sop("x==y:"+(x==y));
		sop("x.equals(y):"+x.equals(y));
	}
	
	public static void method1(){
		Integer x=new Integer(4);
		Integer x1=4;  //          4            new Integer(4);            JDK 5.0   . 
		
		x=x1+2;  //4       ,      +2        .     4:        . x1.intValue();            x
		//x1=x1+2;
		
		
		//    
		Integer m=128;
		Integer n=128;
		sop("m==n:"+(m==n));  //false
		Integer m1=127;
		Integer n1=127;
		sop("m1==n1:"+(m1==n1)); //true ,   m1   n1       Integer  .
		//      byte      .-128~127 ,     ,         ,          .
		sop("m1.compareTo(n1)"+m1.compareTo(n1)); //0   
	}
}