java之String变量和“==”操作符（2）

Java代码
public class StringTest2   
{  
    String s1 = "H";  
    String s2 = "ello";  
    String s3 = s1 + s2;  
    String s4 = "H" + "ello";  
      
    static String ss1 = "H";  
    static String ss2 = "ello";  
    static String ss3 = ss1 + ss2;  
    static String ss4 = "H" + "ello";  
      
    final String fs1 = "H";  
    final String fs2 = "ello";  
    final String fs3 = fs1 + fs2;  
    final String fs4 = "H" + "ello";  
      
    static final String sfs1 = "H";  
    static final String sfs2 = "ello";  
    static final String sfs3 = sfs1 + sfs2;  
    static final String sfs4 = "H" + "ello";  
      
    public static void main(String[] args)  
    {  
        StringTest2 st = new StringTest2();  
        st.test1();  
    }  
      
    public void test1()  
    {  
        String str1 = "H";  
        String str2 = "ello";  
        String str3 = "Hello";  
        String str4 = str1 + str2;  
        String str5 = "H" + "ello";  
          
        //1  
        System.out.println(str3 == str4);  
        System.out.println(str3 == str5);  
          
        //2  
        System.out.println();  
        System.out.println(str3 == s3);  
        System.out.println(str3 == s4);  
          
        //3  
        System.out.println();  
        System.out.println(str3 == ss3);  
        System.out.println(str3 == ss4);  
          
        //4  
        System.out.println();  
        System.out.println(str3 == fs3);  
        System.out.println(str3 == fs4);  
          
        //5  
        System.out.println();  
        System.out.println(str3 == sfs3);  
        System.out.println(str3 == sfs4);  
    }  
} 

public class StringTest2
{
String s1 = "H";
String s2 = "ello";
String s3 = s1 + s2;
String s4 = "H" + "ello";

static String ss1 = "H";
static String ss2 = "ello";
static String ss3 = ss1 + ss2;
static String ss4 = "H" + "ello";

final String fs1 = "H";
final String fs2 = "ello";
final String fs3 = fs1 + fs2;
final String fs4 = "H" + "ello";

static final String sfs1 = "H";
static final String sfs2 = "ello";
static final String sfs3 = sfs1 + sfs2;
static final String sfs4 = "H" + "ello";

public static void main(String[] args)
{
StringTest2 st = new StringTest2();
st.test1();
}

public void test1()
{
String str1 = "H";
String str2 = "ello";
String str3 = "Hello";
String str4 = str1 + str2;
String str5 = "H" + "ello";

//1
System.out.println(str3 == str4);
System.out.println(str3 == str5);

//2
System.out.println();
System.out.println(str3 == s3);
System.out.println(str3 == s4);

//3
System.out.println();
System.out.println(str3 == ss3);
System.out.println(str3 == ss4);

//4
System.out.println();
System.out.println(str3 == fs3);
System.out.println(str3 == fs4);

//5
System.out.println();
System.out.println(str3 == sfs3);
System.out.println(str3 == sfs4);
}
}




输出如下：

Java代码
false 
true 
 
false 
true 
 
false 
true 
 
true 
true 
 
true 
true