[四] java虚拟机JVM编译器编译代码简介 字节码指令实例 代码到底编译成了什么形式详解编程语言

public static void main(String[] args) { 
 
int i = -1; 
int j = 3; 
int k = 5; 
int l = 127; 
int m = 32767; 
int n = 32768; 
 
 
int add = i+j; 
int sub = i-j; 
int mul = j*k; 
int div = j/k; 
int rem = k%j; 
int neg = ~j; 
int inc = i++; 
 
}

public static void main(String[] args) { 
boolean bNum = true; 
 
char cNum = 2; 
byte byteNum = 127; 
short sNum = 32767; 
int iNum = 100; 
long lNum = 65536; 
float fNum = 2.5f; 
double dNum = 6.8; 

 
char c1 = (char)byteNum; 
char c2 = (char)sNum; 
char c3 = (char)iNum; 
char c4 = (char)lNum; 
char c5 = (char)fNum; 
char c6 = (char)dNum; 
 
byte b1 = (byte)cNum; 
byte b2 = (byte)sNum; 
byte b3 = (byte)iNum; 
byte b4 = (byte)lNum; 
byte b5 = (byte)fNum; 
byte b6 = (byte)dNum; 
 
short s1 = (short)cNum; 
short s2 = (short)byteNum; 
short s3 = (short)iNum; 
short s4 = (short)lNum; 
short s5 = (short)fNum; 
short s6 = (short)dNum; 
 
int i1 = (int)cNum; 
int i2 = (int)byteNum; 
int i3 = (int)sNum; 
int i4 = (int)lNum; 
int i5 = (int)fNum; 
int i6 = (int)dNum; 
 
long l1 = (long)byteNum; 
long l2 = (long)cNum; 
long l3 = (long)sNum; 
long l4 = (long)iNum; 
long l5 = (long)fNum; 
long l6 = (long)dNum; 
 
float f1 = (float)byteNum; 
float f2 = (float)cNum; 
float f3 = (float)sNum; 
float f4 = (float)iNum; 
float f5 = (float)lNum; 
float f6 = (float)dNum; 
 
double d1 = (double)byteNum; 
double d2 = (double)cNum; 
double d3 = (double)sNum; 
double d4 = (double)iNum; 
double d5 = (double)lNum; 
double d6 = (double)fNum; 
}

class Super{ 
} 
 
class Sub extends Super{ 
} 
 
new Object(); 
new Super(); 
Super s = new Super(); 
new Double(1.5); 
new Sub(); 
Sub sub = new Sub();

Super super1 = new Super(); 
Sub sub = new Sub(); 
 
//父类引用可以指向子类 
//子类引用不能指向父类 
//但是对于指向子类的父类引用 可以通过类型转换为子类 
Super subToSuper = sub; 
Sub superToSub = (Sub) subToSuper;

void intWhile() { 
int i = 0; 
while (i < 100) { 
i++; 
} 
} 
 
void intDoWhile() { 
int i = 0; 
do { 
i++; 
} 
while (i < 100); 
} 
 
void intFor() { 
int j = 0; 
for(int i =0;i<100;i++) { 
j++; 
} 
}

public void fun() { 
int i = 0; 
if(i<2) { 
i++; 
}else { 
i--; 
} 
}

public void invoker() { 
method(2); 
} 
 
public void method(int i) { 
if(i>5) { 
System.out.println(i); 
} 
}

int i = 5; int j = 6; switch (i) { case 1: j = j + 1; break; case 3: j = j + 2; break; case 5: j = j + 3; break; default: j = j + 4; }

int j = 6; 
String string = "hehe"; 
switch (string) { 
case "A": 
j = j + 1; 
break; 
case "hehe": 
j = j + 2; 
break; 
case "C": 
j = j + 3; 
break; 
default: 
j = j + 4; 
}

int i = 5; 
int j = 8; 
int k = i+j; 
 
int l = 3+6;