JAVA学习日志（数据类型、字符串）
浮点型：
public class TestFloat
{
public static void main (String args[])
{
int i1=1;
int i2=2;
float f1=1f;
float f2=3f;
float result1,result2;
result1=i1/i2;
result2=i1/f2;
System.out.println("result1="+result1);
System.out.println("result2="+result2);
}
}
字符型：
public class TestChar {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
char char1='a';
char char2='a'+1;
char char3='a'-1;
System.out.println(char1);
System.out.println(char2);
System.out.println(char3);
}
}
布尔型：
public class TestBoolean {
public static void main (String args[])
{
boolean b=false;
if(b)
System.out.print("b is "+b+"条件满足，语句执行");
else
System.out.print("b is "+b+"条件 不满足，执行else语句");
}
}
JAVA中的常量：
public class contstants {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
final int APPLE_PRICE_PER_KM;
int weighOfApple;
int money;
APPLE_PRICE_PER_KM=3;
weighOfApple=5;
money=weighOfApple*APPLE_PRICE_PER_KM;
System.out.print("买苹果共花了"+money+"元");
}
}
数据类型的强制转换：
public class Convers {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
double adouble=4.333;
int aint=(int)adouble;
int aint2=257;
byte abyte=(byte)aint2;
System.out.println(aint);
System.out.println(abyte);
}
}
赋值：
public class FuZhi {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
int speed,salary;
float time,basicSalary,prize,distance;
char alphabet;
alphabet='a';
basicSalary=3589.5F;
prize=2152.3F;
speed=30;
time=1.2F;
salary=(int)(basicSalary+prize);
distance=speed*time;
System.out.println("字母alphabet="+alphabet);
System.out.println("基本工资basicSalary="+basicSalary);
System.out.println("奖金prize="+prize);
System.out.println("总工资（转换为整形）salary="+salary);
System.out.println("行驶距离distance="+distance);
}
}
初始化：
public class DefaultValue {
/**
* @param args
*/
static boolean aboolean;
static char achar;
static byte abyte;
static short ashort;
static int aint;
static long along;
static float afloat;
static double adouble;
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println(aboolean);
System.out.println(achar);
System.out.println(abyte);
System.out.println(ashort);
System.out.println(aint);
System.out.println(along);
System.out.println(afloat);
System.out.println(adouble);
}
}
字符串的连接：
public class TestString {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String name="Tom";
String sex="female";
String from="USA";
String info1="name:"+name+" sex:"+sex+" from:"+from;
String info2="name:"+name+"\n"+"sex:"+sex+"\n"+"from:"+from;
System.out.println(info1);
System.out.println(info2);
}
}
转义字符的使用：
public class TranDemo {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String testStr="双引号\"单引号'反斜杠\\下一行\n制表符\t回车\r";
System.out.println(testStr);
System.out.println(testStr.length());//打印出字符串的长度
}
}
字符串的处理：
public class TestString2 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String s1="hello";
String s2="hello";
String s3="hello"+"china";
System.out.println(s1.equals(s2));//比较字符串是否相等
System.out.println(s1==s2);//比较字符串是否同一位置
System.out.println(s1.equals(s3));
System.out.println(s1==s3);
}
}
public class TestString2 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String a="hello";
String b="hello";
String c=new String("hello");
String d=new String("hell0");
System.out.println(a==b);
System.out.println(a==c);
System.out.println(c==d);
}
}