package net.mindview.initialization;
public class Test1 {
public String str;
public static void main(String[] args) {
Test1 t = new Test1();
System.out.println(t.str);
}
}
package net.mindview.initialization;
public class Test2 {
public String str1 = "abc";
public String str2;
public Test2(){
System.out.println(str1);
System.out.println(str2);
this.str2 = "def";
System.out.println(str1);
System.out.println(str2);
}
public static void main(String[] args) {
Test2 t = new Test2();
}
}
创建一个带默认构造器的类, 在构造器中打印一条消息. 为这个类创建一个对象.
package net.mindview.initialization;
public class Test3 {
public Test3(){
System.out.println("默认构造器");
}
public static void main(String[] args) {
Test3 t = new Test3();
}
}
package net.mindview.initialization;
public class Test3 {
public Test3(){
System.out.println("默认构造器");
}
public Test3(String str){
System.out.println("有一个参数的构造器");
System.out.println(str);
}
public static void main(String[] args) {
Test3 t = new Test3();
Test3 t2 = new Test3("hello");
}
}
package net.mindview.initialization;
public class Dog {
public void bark(){
System.out.println("barking");
}
public void bark(String paoxiao){
System.out.println("howling");
}
public static void main(String[] args) {
Dog dog1 = new Dog();
dog1.bark();
dog1.bark("paoxiao");
}
}
package net.mindview.initialization;
public class Test8 {
public void method1(){
System.out.println("1");
method2().method2();
}
public Test8 method2(){
System.out.println("2");
return this;
}
public static void main(String[] args) {
Test8 t = new Test8();
t.method1();
}
}
package net.mindview.initialization;
public class Test17 {
public Test17(String str){
System.out.println(str);
}
public static void main(String[] args) {
Test17[] tt = null;
}
}
通过创建对象赋值给引用数组,从而完成前一个练习。
package net.mindview.initialization;
import java.util.Random;
public class Test17 {
public Test17(String str){
System.out.println(str);
}
public static void main(String[] args) {
Random rand = new Random();
Test17[] tt = new Test17[rand.nextInt(100)];
for(int i=0;i<tt.length; i++){
tt[i] = new Test17(""+i);
}
}
}
package net.mindview.initialization;
enum Money{
ONE,
TWO,
FIVE,
TEN,
FIVTY,
HUNDRED
}
public class Test21 {
public static void main(String[] args) {
for(Money m : Money.values()){
System.out.println(m + " " + m.ordinal());
}
}
}
在前面的例子中,为enum写一个switch语句,对于每一个case,输出该特定货币的描述。
package net.mindview.initialization;
enum Money{
ONE,
TWO,
FIVE,
TEN,
FIFTY,
HUNDRED
}
public class Test22 {
Money value;
public Test22(Money value){
this.value = value;
}
public void printValue(){
switch(value){
case ONE:
System.out.println("1元面值");
break;
case TWO:
System.out.println("2元面值");
break;
case FIVE:
System.out.println("5元面值");
break;
case TEN:
System.out.println("10元面值");
break;
case FIFTY:
System.out.println("50元面值");
break;
case HUNDRED:
System.out.println("100元面值");
break;
}
}
public static void main(String[] args) {
Test22 t = new Test22(Money.ONE);
Test22 t2 = new Test22(Money.TWO);
Test22 t3 = new Test22(Money.HUNDRED);
t.printValue();
t2.printValue();
t3.printValue();
}
}