摘要： class Animal{ void cry(){}}class Dog extends Animal{void cry(){ System.out.println("wang!wang!......");}}class Cat extends Animal{ void cry(){System.out.println("miao~~miao~~...");}}public class Example5_9{public static void main(String arg[]){Animal animal; animal=new Dog(); ani 阅读全文

摘要： class A{ double n; int m;void f(){ System.out.printf("子类继承方法f(),n=%f,m=%d\n",n,m);}void g(){ System.out.printf("你好,n=%f,m=%d\n",n,m);}}class B extends A{int n=12; void g(){System.out.printf("子类重写方法g(),n=%d,m=%d\n",n,m);}void cry(){System.out.printf("子类新增的方法,n=%d,m= 阅读全文

摘要： class A{int x,y;A(){x=100;y=200;}A(int x,int y){this.x=x;this.y=y;}}class B extends A{int z;B(int x,int y){super(x,y);z=300;}B(){super();z=800;}public void f(){System.out.printf("x=%d,y=%d,z=%d\n",x,y,z);}}public class Example5_6{public static void main(String arg[]){B b1=new B(10,20);b1.f 阅读全文

摘要： class A{public double y=11.456789;public void f(){y=y+1;System.out.printf("y是double型的变量,y=%f\n",y);}}class B extends A{int y=0;public void g(){y=y+100;System.out.printf("y是int型的变量,y=%d\n",y);}}public class Example5_3{public static void main(String arg[]){B b=new B();b.y=200;b.g() 阅读全文

摘要： class A{private int x=10;protected int y=20;void f(){y=y+x;System.out.printf("x=%d,y=%d\n",x,y);}}class B extends A{void g(){y=y+1;System.out.printf("y=%d\n",y);}}public class Example5_2{public static void main(String arg[]){B b=new B();b.g();b.f();b.g();}} 阅读全文

摘要： public class Example4_18{public static void main (String arg[]){char a[]={'a','b','c','D','E','F'};for(int i=0;i<a.length;i++){if(Character.isLowerCase(a[i])){a[i]=Character.toUpperCase(a[i]);}else if(Character.isUpperCase(a[i])){a[i]=Character.toLo 阅读全文