1.
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class AA extends Applet {
? private int count = 0;
? private Button
??? onOff = new Button("Toggle"),
??? start = new Button("Start");
? private TextField t = new TextField(10);
? private boolean runFlag = true;
? public void init() {
??? add(t);
??? start.addActionListener(new StartL());
??? add(start);
??? onOff.addActionListener(new OnOffL());
??? add(onOff);
? }
? public void go() {
??? while (true) {
????? try {
??????? Thread.currentThread().sleep(100);
????? } catch (InterruptedException e){}
????? if(runFlag)
??????? t.setText(Integer.toString(count++));
??? }
? }
? class StartL implements ActionListener {
??? public void actionPerformed(ActionEvent e) {
????? go();
??? }
? }
? class OnOffL implements ActionListener {
??? public void actionPerformed(ActionEvent e) {
????? runFlag = !runFlag;
??? }
? }
? public static void main(String[] args) {
??? AA applet = new AA();
??? Frame aFrame = new Frame("AA");
??? aFrame.addWindowListener(
????? new WindowAdapter() {
??????? public void windowClosing(WindowEvent e) {
????????? System.exit(0);
??????? }
????? });
??? aFrame.add(applet, BorderLayout.CENTER);
??? aFrame.setSize(300,200);
??? applet.init();
??? applet.start();
??? aFrame.setVisible(true);
? }
} ///:~
2。
class SuperClass
{
?int a = 3,b = 6;}
class SubClass extends SuperClass
{
//?int a=30,b=20;
?int max(){return ((a > b)? a:b);}}
public class ABC {
?public static void main(String[] args) {
?SubClass sb = new SubClass();
?System.out.println(sb.max());
?}
}
3.
?? interface? Playable?? {
?????? void? play();
? }
??? interface? Bounceable?? {
?????? void? play();
? }
??? interface? Rollable? extends? Playable, Bounceable?? {
????? Ball ball? =?? new? Ball( " PingPang " );//interface 里面的變量為public static final
? }
??? class? Ball? implements? Rollable?? {
?????? private? String name;
??????? public? String getName()?? {
?????????? return? name;
????? }
??????? public? Ball(String name)?? {
????????? this .name? =? name;???????
????? }
????? public?? void? play()?? {
//????????? ball? =?? new? Ball( " Football " );
????????? System.out.println(ball.getName());
????? }
? }
4.
public class BB {
?String a ;
public BB(String a){
?this.a = a;
?System.out.println("11");
}
?public static void main(String[] args) {
??String s = new String ("Computer");
??if(s == "Computer")
???System.out.println("Equal A");
??if(s.equals("Computer"))
???System.out.println("Equal B");
??BB b = new BB("aa");
??BB c = new BB("aa");
??BB d ;
??d = c;
??
??if(b == c)
???System.out.println("Equal b=c");
??if(b.equals("aa"))
???System.out.println("Equal b equals 'aa'");
??if(d.equals("aa"))
???System.out.println("Equal d equals 'aa'");
??if(d.equals(c))
???System.out.println("Equal d equals 'c'");
??if(d==c)
???System.out.println("Equal d equals 'c'");
?}
}
5.
interface? A{
??? int x = 0;
?}
?class B{
??? int x =1;
?}
?class C extends B implements A {
??? public void pX(){
//?????? System.out.println(x);//兩個x都匹配,對于父類的變量,可以用super.x來明確，而接口的屬性默認隱含為 public static final.所以可以通過A.x來明確。
??? }
??? public static void main(String[] args) {
?????? new C().pX();
??? }
?}
6.
public class CalC {
???? void amethod(){
??????? System.out.println("CalC.amethod");
????? }
????? CalC(){//---------〉3
???????? amethod();//----〉4
????????? System.out.println("Hu?");
???? }
???? public static void main(String[] args) {
???????? // TODO Auto-generated method stub
???????? CalC cc = new CalChild();//--1初始化調(diào)用構(gòu)造方法，向上轉(zhuǎn)型，調(diào)用弗雷構(gòu)造方法
???????? System.out.println("1");
???????? cc.amethod();
???? }
?}
?class CalChild extends CalC{
??//----2
???? void amethod(){//-----5
??????? System.out.println("CalChild.amethod");
??? }
?}
7.
class Vehicle{
?String str;
?public Vehicle(){}
?public Vehicle(String s){
??
?}
}
?public class Car {
?String a;
? public Car(String a){this.a = a;}
?public static void main(String[] args) {
?? Vehicle v = new Vehicle("Hello");
?? Car a;
//?? a = "a";
??v = new Vehicle ("How are You");
??v.str = "How is going";
??System.out.println("Greeting is :" + v+"11");
?}
}
8.
class? Parent{
?private void method1(){
??System.out.println("Parent's method1()");
?}
?public void method2(){
??System.out.println("Parent's method2()");
??method1();
?}
}
public class Childe extends Parent {
?public void method1(){
??System.out.println("Child's method1()");
?}
?
?public static void main(String[] args) {
?Parent p = new Childe();
?p.method2();
?}
}?????????
9.
class?? O?? {??
??????? public?? O()?? {??
?????????? System.out.println("A's?? c?? is?? here?? ");??
????? }??
?????? void?? println()? {??
?????????? System.out.println("A's?? v?? is?? here?? ");??
?????? }??
??? }??
?class?? P?? extends? O {??
?????? public?? P()?? {??
?????????? System.out.println("B's?? c?? is?? here?? ");??
?????? }??
?????? void?? println()? {??
?????????? System.out.println("B's?? v?? is?? here?? ");??
?????? }??
?? }??
?? public?? class?? Chp_4_2? {??
?????? public?? static?? void?? main(String[]?? args)? {??
?????????? O?? b?? =?? new?? P();
?????????? b.println();
?????? }??
? }
10.
public class Cwich {
?/**
? * @param args
? */
?public static void main(String[] args) {
??int x = 9;
??switch(x){
??default:
???System.out.println(1);
??case 1:
??System.out.println(1);
??case 2:
??case 3:
???System.out.println(3);break;
??case 4:
???System.out.println("4");
//??default:
//???break;
??}
11.
class Tree{}
class Pine extends Tree{}
class Oak extends Tree{}
public class Forest {
?public static void main(String[] args) {
??
??Tree tree = new Pine();
??if(tree instanceof Pine)
???System.out.println("Pine");
??if(tree instanceof Tree)
???System.out.println("Tree");
??if(tree instanceof Oak)
???System.out.println("Oak");
??else
???System.out.println("Oops");
?}
}
12.
class FuZhia {
? private int a;
?? public int change(int m) {
???? return m;??
?? }?
???
?}
?public class FuZhi extends FuZhia{
?? public int b;?
? public static void main() {
?? FuZhi? aa = new FuZhi();
?? FuZhia? bb = new FuZhia();
??? int k;?
??? k=bb.change(30);?
?? }
?}
13.
import java.sql.*;
public class Jdbc
{
String dbUrl="jdbc:oracle:thin:@127.0.0.1:1521:orcl";
String theUser="admin";
String thePw="manager";
Connection c=null;
Statement conn;
ResultSet rs=null;
public Jdbc()
{
try{
Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
c = DriverManager.getConnection(dbUrl,theUser,thePw);
conn=c.createStatement();
}catch(Exception e){
e.printStackTrace();
}
}
public boolean executeUpdate(String sql)
{
try
{
conn.executeUpdate(sql);
return true;
}
catch (SQLException e)
{
e.printStackTrace();
return false;
}
}
public ResultSet executeQuery(String sql)
{
rs=null;
try
{
rs=conn.executeQuery(sql);
}
catch (SQLException e)
{
e.printStackTrace();
}
return rs;
}
public void close()
{
try
{
conn.close();
c.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
public static void main(String[] args)
{
ResultSet rs;
Jdbc conn = new Jdbc();
rs=conn.executeQuery("select * from test");
try{
while (rs.next())
{
System.out.println(rs.getString("id"));
System.out.println(rs.getString("name"));
}
}catch(Exception e)
{
e.printStackTrace();
}
}
}
14.
class AB {
?String s1;
?String s2;
?AB(String str1,String str2){
??s1 = str1;s2 = str2;
?}
?public String toString(){
??return s1+s2;
?}
}
public class jiahao {
?public static void main(String[] args) {
??AB s = new AB("Hello!","I love Java.");
??System.out.println(s.toString());
?}
}
15.
class N{
?N(){
??System.out.println("Class N Constructor");
?}
}
public class M extends N{
?M(){System.out.println("Class M Constructor");}
?
?public static void main(String[] args) {
??M m = new M();
?}
}
16.
?? class? Base? {
???????? private? final? void? f()? {? //注意final
?????????? System.out.println( " Base.f() " );
//?????????? public int i;//局部變量前不能放置任何修飾符
?????? }
?? }
??
??? class? Derived? extends? Base? {
???????? public? final? void? f()? {?? //注意final
????????? System.out.println( " Derived.f() " );
????? }
? }
??
??? public?? class? Main?? {
??????????? public?? static?? void? main(String[] args)?? {
????????? Derived op1? =?? new? Derived();
???????? Base op2 = op1;
????????? op1.f();
//???????? op2.f();
????? }
?}
17.
import java.awt.AWTEvent;
import java.awt.TextArea;
import java.awt.event.TextEvent;
public class MyTextArea extends TextArea{
?public MyTextArea(int nrows,int ncols){
??enableEvents(AWTEvent.TEXT_EVENT_MASK);
?}
?public void processTextEvent(TextEvent te){
??System.out.println("Processing a text event.");
?}
}
18.
public class Outer {
?final String s = "i am outer class member variable";
?public void Method(){
??String s1 = "i am inner class variable";
??class InnerClass{
???String s2 = "i am inner class variable";
???public void innerMethod(){
????int xyz = 20;
????System.out.println(s);
????System.out.println("Integer value is " + xyz);
????System.out.println(s2);
???}
??}
?}
?public static void main(String[] args) {
??// TODO Auto-generated method stub
?}
}
19.
public class Outerclass
{
private class InterClass
{
public InterClass()
{
System.out.println("InterClass Create");
}
}
public Outerclass()
{
InterClass ic = new InterClass();
System.out.println("OuterClass Create");
}
public static void main(String[] args)
{
Outerclass oc = new Outerclass();
}
}
20.
public class Parent1 {
? public void test(){ }
? public Parent1(){
???????? test();
??? }
? public static void main(String[] args){
???????? new Child1();
???? }
}
class Child1 extends Parent1{
??????? public int instanceValue = 20;
??????? public Child1(){
??????? ????? //super();
??????? ????? System.out.println("instance value isa: " + instanceValue);
??????? ? }
??? public void test(){
??????????? System.out.println("instance value is: " + instanceValue);
?????? }
? }