JAvaにおけるInteger,String判定等とintegerの比較サイズ

package sfk.bbs.test.springjsbctempletTest;

import static org.junit.Assert.*;

import org.junit.Test; public class testBase { @Test public void test() { Integer tt2 = -129; Integer tt = new Integer(-129);//   Integer tt2 = -129;,       [-128,127]     Integer tt2 = -129;   new     integer  
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 System.out.println(tt == tt2);//          ,   new integer  ,         .         .==             ,                System.out.println(tt.equals(tt2));//equals      ,                  int     ,   int     .    true System.out.println(tt > tt2);//           int , System.out.println(tt < tt2); //System.out.println(tt + tt2); /** * false * true * false * false */ } }

　
拡張版

package sfk.bbs.test.springjsbctempletTest;


import org.junit.Test;

public class testBase
{

    @Test
    public void test()
    {
   
       /*  
        *  public static Integer valueOf(int i) {
            if (i >= IntegerCache.low && i <= IntegerCache.high)
                return IntegerCache.cache[i + (-IntegerCache.low)];
            return new Integer(i);
        }*/

        //    
        //     [-128,127]          Integer  ,        cache        ,       [-128,127]            integer   ,
        //               .  a       true
        
        Integer autoPackage0 = Integer.valueOf(1);
        /**
         * public static Integer valueOf(int i) {
        if (i >= IntegerCache.low && i <= IntegerCache.high)
            return IntegerCache.cache[i + (-IntegerCache.low)];
        return new Integer(i);
            }
         */
        //     ,           ,    Integer.valueOf(int i)    
        //              
        Integer autoPacking1 = 1;
        Integer autoPacking2 = 1;
        Integer newInteger = new Integer(1);
        System.out.println(" integer cache  ");
        //equeals   
        System.out.println("autoPacking1.equals(autoPacking2) : "+autoPacking1.equals(autoPacking2));//true         Integer           
        System.out.println("autoPacking1.equals(newInteger) : "+autoPacking1.equals(newInteger));//true,,            Integercache  
        
        //    
        System.out.println("autoPacking1==autoPacking2 : "+(autoPacking1==autoPacking2));//true,      
        System.out.println("autoPacking1==newInteger : "+(autoPacking1==newInteger));//fasle,new               ,      
        
        System.out.println("  integer cache  ");
        //
        
        Integer autoPacking3 = Integer.valueOf(128);
        Integer autoPacking4 = 128;
        Integer autoPacking5 = 128;
        Integer newIntger2 = new Integer(128);
        System.out.println("autoPacking5==autoPacking4 : "+(autoPacking5==autoPacking4));//a   false,    cache       ,  Integer.valueOf(int i)  .
        System.out.println("autoPacking3==autoPacking4 : "+(autoPacking3==autoPacking4));//   false,        ,        ,   false
        System.out.println("autoPacking4==newIntger2 : "+(autoPacking4==newIntger2));//  false
        System.out.println(" Integer         (>,=,<=)       ,      value  ");
        System.out.println(autoPacking4.intValue()==autoPacking4.intValue());//                 ,   intValue  
    }
    @Test
    public void testString()
    {
        /**
         * String  equals                 ,      ,      true,
         *        ,     ,                   ,       ,    true
          public boolean equals(Object anObject) {
        if (this == anObject) {
            return true;
        }
        if (anObject instanceof String) {
            String anotherString = (String)anObject;
            int n = value.length;
            if (n == anotherString.value.length) {
                char v1[] = value;
                char v2[] = anotherString.value;
                int i = 0;
                while (n-- != 0) {
                    if (v1[i] != v2[i])
                        return false;
                    i++;
                }
                return true;
            }
        }
        return false;
    }

         */
        System.out.println("      ,      new                       ,        ,        (     )     ");
        String s1 = "qq";
        String s11 = "qq";
        
        String s2 = new String("qq");
        //  
        System.out.println("s1==s11 : "+(s1==s11));//         java     
        //          qq String  ,          ,      
        //String s11 = "qq";   ,                String     ,   "qq"
        //          ,             String  ,              String  
        //             
        
        System.out.println("s1==s2 : "+(s1==s2));
        
        //equals
        System.out.println("s1.equals(s11) : "+s1.equals(s11));//true  equals           true
        System.out.println("s1.equals(s11) : "+s1.equals(s11));//true  equals           true
        System.out.println("s1.equals(s11) : "+s1.equals(s11));//true  equals           true
        //String      Integer         
        
        
    }
 

}

 
 

    

http://bbs.csdn.net/topics/392029500

http://www.cnblogs.com/danne823/archive/2011/04/22/2025332.html