华恩JAVA班第12天
一 基本类型：基本类型，或者叫做内置类型，是JAVA中不同于类的特殊类型。
数据类型 大小 范围 默认值 byte(字节) 8 -128 - 127 0 shot(短整型) 16 -32768 - 32768 0 int(整型) 32 -2147483648-2147483648 0 long(长整型) 64 -9233372036854477808-9233372036854477808 0 float(浮点型) 32 -3.40292347E+38-3.40292347E+38 0.0f double(双精度) 64 -1.79769313486231570E+308-1.79769313486231570E+308 0.0d char(字符型) 16 ‘ \u0000 - u\ffff ’ ‘\u0000 ’ boolean(布尔型) 1 true/false false 包装类型：包装类型/引用 int Integer long Long float Float double Double byte Byte ... ... 二、 基本类型比较：== 内存地址比较 引用类型比较：equals 值比较 ==： public class Test { public static void main(String[] args) { int a = 1,b = 1; Integer c = 1; Integer d = new Integer(1); //new 强制开辟一个空间 Integer e = new Integer(1); Integer f = c; System.out.println(c == d);// c与d的地址不同， System.out.println(c.equals(d)); // 值比较 System.out.println(c == b); System.out.println(b == d); System.out.println(c == f); System.out.println(e == d); } } equals： class Dog{ String name; String zl; public boolean equals(Object anObject){ if(this == anObject){ return true; } if(anObject instanceof Dog){ Dog dog = (Dog) anObject; if(dog.name.equals(this.name)){ return true; }else{ return false; } }else{ return false; } } } public class Test2 { public static void main(String[] args){ Dog dog1 = new Dog(); Dog dog2 = new Dog(); dog1.name = "tom"; dog2.name = "tom"; dog1.zl = "哈士奇"; dog2.zl = "哈士奇"; System.out.println(dog1.equals(dog2)); } } 三、 import java.util.*; public class Test { public static void main(String[] args){ Scanner in =new Scanner(System.in); int A = in.nextInt(); for(int a = 0 ;a <= A;a++){ for(int b = 0;b < A-a+1;b++){ System.out.print(" "); } for(int i = 0;i < 2*a-1;i++){ System.out.print("*"); } System.out.println(); } } }