java基础类学习_java常用基础类

java基础类学习_java常用基础类。

1.基本数据类型对应的包装类
基本数据类型 对应的包装类
boolean Boolean
byte Byte
short Short
int Long
char Character
float Float
double Double

String转基本数据类型

String转int:
int i = Integer.decode(“123”);
System.out.println(i/2);

String转float:
float f = Float.parseFloat(“1”);
System.out.println(f+2);;

String转double:
double d = Double.parseDouble(“2.2554”);
System.out.println(d+10);

String转byte:
byte b = Byte.parseByte(“10”);
System.out.println(b+10);

String转long://两个方法结果一样
long l = Long.parseLong(“123456789”);//将 string 参数解析为有符号十进制 long。
System.out.println(l);
long lo = Long.decode(“123456789”);//将 String 解码成 Long。
System.out.println(l);

String转boolean:
boolean bo = Boolean.parseBoolean(“00”);//将字符串参数解析为 boolean 值。
System.out.println(bo);

String转char:——-
String str1=”abc”;
char c=str1.charAt(0);
System.out.println((int)c+” “+c);//int(c)表示在ASCII表中的位数

String转short:
short s = Short.parseShort(“12356”);
System.out.println(s);

基本数据类型转String
int转String:
int a1=12;
String s1 = String.valueOf(a1);
System.out.println(s1);
byte转String:
byte b = 0;
String s4 = String.valueOf(b);
System.out.println(s4);
short转String:
short s=100;
String s5 = String.valueOf(s);
System.out.println(s5);

float转String:
float f=12;
String s7 = String.valueOf(f);
System.out.println(s7);

double转String:
double d = 5;
String s6 = String.valueOf(d);
System.out.println(s6);

boolean转String:
boolean bo = false;
String s2 = String.valueOf(bo);
System.out.println(s2);

char转String:
char c =’a’;
String s8 = String.valueOf(c);
System.out.println(s8);

short转String
short s=100;
String s5 = String.valueOf(s);
System.out.println(s5);