Java从入门到实战之（24）Java 方法处理之练习-白红宇的个人博客

Java从入门到实战之（24）Java 方法处理之练习

发布日期：2021-05-14 00:18:15 浏览次数：15 分类：博客文章

本文共 40753 字，大约阅读时间需要 135 分钟。

1��

��Overloading��

��

��

��

��

main ��

package Java_Learn.File;class  MyClass{    int height;    public MyClass() {        System.out.println("������������������");        height =100;    }    public MyClass(int height)    {        this.height=height;        System.out.println("���������������������"+height+"���");    }    public void info()    {        System.out.println("���������������������"+height+"���");    }    public void info(String s)    {        System.out.println(s+"���������������������"+height+"���");    }}public class Main1 {    public static void main(String[] args) {        MyClass t=new MyClass(3);        t.info();        t.info("���������������");        //������������������        new MyClass();    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=52752:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1���������������������3������������������������3������������������������������������3���������������������Process finished with exit code 0

2��

��

��(Overloading)����

��Overriding����

package Java_Learn.File;class Figure{    double dim1;    double dim2;    Figure(double a , double b) {        dim1=a;        dim2=b;    }    Double area() {        System.out.println("������������");        return(dim1*dim2);    }}class Rectangle extends Figure {    Rectangle(double a, double b) {        super(a ,b);    }//    ���������������������������������������������������������    Double area() {        System.out.println("������������");        return(dim1*dim2);    }}public class Main1 {    public static void main(String[] args) {        Figure f= new Figure(10 , 10);        Rectangle r= new Rectangle(9 , 5);        Figure figref;        figref=f;        System.out.println("������������������ :"+figref.area());//        ������������������������������������������������������������������        figref=r;        System.out.println("��������������������� :"+figref.area());    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=52854:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1������������������������������ :100.0��������������������������������� :45.0Process finished with exit code 0

3��(overloading)�� Varargs

��

package Java_Learn.File;public class Main1 {    static void vaTest(int ... no) {        System.out.print("vaTest(int ...): "                + "������������: " + no.length +" ������: ");        for(int n : no)            System.out.print(n + " ");        System.out.println();    }    static void vaTest(boolean ... bl) {        System.out.print("vaTest(boolean ...) " +                "������������: " + bl.length + " ������: ");        for(boolean b : bl)            System.out.print(b + " ");        System.out.println();    }    static void vaTest(String msg, int ... no) {        System.out.print("vaTest(String, int ...): " +                msg +"������������: "+ no.length +" ������: ");        for(int  n : no)            System.out.print(n + " ");        System.out.println();    }    public static void main(String args[]){        vaTest(1, 2, 3);        vaTest(true, false, false);        vaTest("������: ", 10, 20);    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=52917:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1vaTest(int ...): ������������: 3 ������: 1 2 3 vaTest(boolean ...) ������������: 3 ������: true false false vaTest(String, int ...): ������: ������������: 2 ������: 10 20 Process finished with exit code 0

4��Varargs ��

Java1.5��varargs��

"Varargs"��"variable number of arguments"��"variable arguments"

��"��"��"��"��"."��"..."��

package Java_Learn.File;public class Main1 {    public static void main(String args[]){        int sum=0;        sum=sumArr(new int[]{10,12,13});        System.out.println("���������������������:"+sum);    }    private static int sumArr(int ... intArr)    {        int sum = 0,i;        for(i=0;i

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53075:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1���������������������:35Process finished with exit code 0

5��instanceof ��

instanceof �� Java �� ==��>��< ��

instanceof �� Java �� boolean ��

package Java_Learn.File;import java.util.ArrayList;import java.util.Vector;class Student{    public Student()    {    }}public class Main1 {    public static void main(String args[]){        Object arr=new ArrayList();        showObjectClass(arr);        Object student=new Student();        showObjectClass(student);    }    private static void showObjectClass(Object o)    {        if(o instanceof Vector)            System.out.println("��������� java.util.Vector ������������");        else if(o instanceof ArrayList)            System.out.println("��������� java.util.ArrayList ������������");        else            System.out.println("������������"+o.getClass()+"������������");    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53173:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1��������� java.util.ArrayList ������������������������class Java_Learn.File.Student������������Process finished with exit code 0

6��

Java �� break ��coutinue ��

�� break �� continue ��

public class Main {    public static void main(String[] args) {        String strSearch = "This is the string in which you have to search for a substring.";        String substring = "substring";        boolean found = false;        int max = strSearch.length() - substring.length();        testlbl:        for (int i = 0; i <= max; i++) {            int length = substring.length();            int j = i;            int k = 0;            while (length-- != 0) {                if(strSearch.charAt(j++) != substring.charAt(k++)){                    continue testlbl;                }            }            found = true;            break testlbl;        }        if (found) {            System.out.println("���������������������");        }        else {            System.out.println("���������������������������������������");        }    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53238:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1���������������������Process finished with exit code 0

7��Enum��

��Enum��

package Java_Learn.File;enum Car{    lamborghini(900),tata(2),audi(50),fiat(15),honda(12);    private int price;    Car(int price) {        this.price=price;    }    int getPrice()    {        return price;    }}public class Main1 {    public static void main(String[] args) {        System.out.println("���������������������:");        for(Car car:Car.values())        {            System.out.println(car+"������"+car.getPrice()+"������������");        }    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53319:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1���������������������:lamborghini������900������������tata������2������������audi������50������������fiat������15������������honda������12������������Process finished with exit code 0

8��enum �� switch ��

Java �� enum �� java.lang.Enum ��

��enum��switch��

package Java_Learn.File;import java.util.Scanner;enum Car {    lamborghini,tata,audi,fiat,honda}public class Main1 {    public static void main(String args[]){        Scanner scanner=new Scanner(System.in);       Car c=Car.valueOf(scanner.next());        switch(c) {            case lamborghini:                System.out.println("������������ lamborghini!");                break;            case tata:                System.out.println("������������ tata!");                break;            case audi:                System.out.println("������������ audi!");                break;            case fiat:                System.out.println("������������ fiat!");                break;            case honda:                System.out.println("������������ honda!");                break;            default:                System.out.println("���������������������������");                break;        }    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53787:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1tata������������ tata!Process finished with exit code 0

9��for �� foreach��

for ��

for��

for(���������; ���������������; ������) { //������������}

foreach��java5��foreach��

foreach ��

for(������������t ������������x : ������������obj){ ���������x���java������; }

�� for �� foreach��

Main.java ��

public class Main {    public static void main(String[] args) {        int[] intary = { 1,2,3,4};        forDisplay(intary);        foreachDisplay(intary);    }    public static void forDisplay(int[] a){          System.out.println("������ for ������������");        for (int i = 0; i < a.length; i++) {            System.out.print(a[i] + " ");        }        System.out.println();    }    public static void foreachDisplay(int[] data){        System.out.println("������ foreach ������������");        for (int a  : data) {            System.out.print(a+ " ");        }    }}

��

������ for ������������1 2 3 4 ������ foreach ������������1 2 3 4

Main.java ��

import java.util.ArrayList;import java.util.Iterator;import java.util.List; public class Main{    public static void main(String[] args)    {        int[] arr = {1, 2, 3, 4, 5};                System.out.println("----------������ for ������------------");        for(int i=0; i
       
         list = new ArrayList
        
         ();                list.add("Google");        list.add("Runoob");        list.add("Taobao");                System.out.println("----------������1���������for������-----------");        for(int i = 0; i < list.size(); i++)        {            System.out.println(list.get(i));        }                System.out.println("----------������2������������������-----------");        for(Iterator
         
           iter = list.iterator(); iter.hasNext();)        {            System.out.println(iter.next());        }                System.out.println("----------������3���For-Each ������-----------");        for(String str: list)        {            System.out.println(str);        }    }}

������������������������������������----------������ for ������------------12345---------������ For-Each ������-------------12345---------For-Each ������������������-------------123456789----------������1���������for������-----------GoogleRunoobTaobao----------������2������������������-----------GoogleRunoobTaobao----------������3���For-Each ������-----------GoogleRunoobTaobao

10��break ��

Java break ��

public class Main {    public static void main(String[] args) {        int[] intary = { 99,12,22,34,45,67,5678,8990 };        int no = 5678;        int i = 0;        boolean found = false;        for ( ; i < intary.length; i++) {            if (intary[i] == no) {                found = true;                break;            }        }        if (found) {            System.out.println(no + " ������������������������: " + i);        }         else {            System.out.println(no + " ���������������������");        }    }}

��

5678 ������������������������: 6

11��continue ��

Java continue ��

public class Main {    public static void main(String[] args) {        StringBuffer searchstr = new StringBuffer("hello how are you. ");        int length = searchstr.length();        int count = 0;        for (int i = 0; i < length; i++) {            if (searchstr.charAt(i) != 'h')            continue;            count++;            searchstr.setCharAt(i, 'h');        }        System.out.println("������ " + count         + " ��� h ������");        System.out.println(searchstr);    }}

��

������ 2 ��� h ������hello how are you.

12��

�� MainClass �� printArray ��(��, ��)��

public class MainClass {    public static void printArray(Integer[] inputArray) {        for (Integer element : inputArray){            System.out.printf("%s ", element);            System.out.println();        }    }    public static void printArray(Double[] inputArray) {        for (Double element : inputArray){            System.out.printf("%s ", element);            System.out.println();        }    }    public static void printArray(Character[] inputArray) {        for (Character element : inputArray){            System.out.printf("%s ", element);            System.out.println();        }    }    public static void main(String args[]) {        Integer[] integerArray = { 1, 2, 3, 4, 5, 6 };        Double[] doubleArray = { 1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7 };        Character[] characterArray = { 'H', 'E', 'L', 'L', 'O' };        System.out.println("������������������:");        printArray(integerArray);        System.out.println("\n������������������������:");        printArray(doubleArray);        System.out.println("\n���������������������:");        printArray(characterArray);    }}

��

������������������:1 2 3 4 5 6 ������������������������:1.1 2.2 3.3 4.4 5.5 6.6 7.7 ���������������������:H E L L O

13��

��64��

��:

1.��A,B,C��A��

2.��,��

3.��A��C��

��

public class MainClass {    public static void main(String[] args) {        int nDisks = 3;        doTowers(nDisks, 'A', 'B', 'C');    }    public static void doTowers(int topN, char from, char inter, char to) {        if (topN == 1){            System.out.println("Disk 1 from "            + from + " to " + to);        }else {            doTowers(topN - 1, from, to, inter);            System.out.println("Disk "            + topN + " from " + from + " to " + to);            doTowers(topN - 1, inter, from, to);        }    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53944:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1Disk 1 from A to CDisk 2 from A to BDisk 1 from C to BDisk 3 from A to CDisk 1 from B to ADisk 2 from B to CDisk 1 from A to CProcess finished with exit code 0

14��

�� 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233��377��610��987��1597��2584��4181��6765��10946��17711��28657��46368��

��0��0��1��1��

��

�� Java ��

package Java_Learn.File;public class Main1 {    public static long fibonacci(long number) {        if ((number == 0) || (number == 1))            return number;        else            return fibonacci(number - 1) + fibonacci(number - 2);    }    public static void main(String[] args) {        for (int counter = 0; counter <= 10; counter++){            System.out.printf("Fibonacci of %d is: %d\n",                    counter, fibonacci(counter));        }    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53979:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main1Fibonacci of 0 is: 0Fibonacci of 1 is: 1Fibonacci of 2 is: 1Fibonacci of 3 is: 2Fibonacci of 4 is: 3Fibonacci of 5 is: 5Fibonacci of 6 is: 8Fibonacci of 7 is: 13Fibonacci of 8 is: 21Fibonacci of 9 is: 34Fibonacci of 10 is: 55Process finished with exit code 0

15��

��factorial��0��1��n��n!��

��n!=1��2��3��...��n��0!=1��n!=(n-1)!��n��

package Java_Learn.File;public class Main1 {    public static void main(String args[]) {        for (int counter = 0; counter <= 10; counter++){            System.out.printf("%d! = %d\n", counter,                    factorial(counter));        }    }    public static long factorial(long number) {        if (number <= 1)            return 1;        else            return number * factorial(number - 1);    }}

��

"C:\Program Files\Java\jdk1.8.0_221\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=53995:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_221\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_221\jre\lib\rt.jar;C:\app\WorkSpace\target\classes;C:\Program Files (x86)\scala\lib\scala-actors-2.11.0.jar;C:\Program Files (x86)\scala\lib\scala-actors-migration_2.11-1.1.0.jar;C:\Program Files (x86)\scala\lib\scala-library.jar;C:\Program Files (x86)\scala\lib\scala-parser-combinators_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-reflect.jar;C:\Program Files (x86)\scala\lib\scala-swing_2.11-1.0.1.jar;C:\Program Files (x86)\scala\lib\scala-xml_2.11-1.0.1.jar;C:\repository\org\scala-lang\scala-library\2.11.0\scala-library-2.11.0.jar" Java_Learn.File.Main10! = 11! = 12! = 23! = 64! = 245! = 1206! = 7207! = 50408! = 403209! = 36288010! = 3628800Process finished with exit code 0

上一篇：Java从入门到实战之（25）Java图形打印之练习

下一篇：Java从入门到实战之（23）时间处理之练习

发表评论

关于作者

喝酒易醉，品茶养心，人生如梦，品茶悟道，何以解忧？唯有杜康！

-- 愿君每日到此一游！

1��

2��

3��(overloading)�� Varargs

4��Varargs ��

5��instanceof ��

6��

7��Enum��

8��enum �� switch ��

9��for �� foreach��

Main.java ��

Main.java ��

10��break ��

11��continue ��

12��

13��

14��

15��

发表评论

最新留言

关于作者

推荐文章

1���������������

2���������������

3���������(overloading)��������������� Varargs

4���Varargs ������������������

5���instanceof ���������������

6���������

7���Enum������������������������������������������

8���enum ��� switch ������������

9���for ��� foreach������������

Main.java ������

Main.java ������

10���break ���������������

11���continue ���������������

12���������������������

13������������������

14���������������������

15���������

发表评论

最新留言

关于作者

推荐文章

1��

2��

3��(overloading)�� Varargs

4��Varargs ��

5��instanceof ��

6��

7��Enum��

8��enum �� switch ��

9��for �� foreach��

Main.java ��

Main.java ��

10��break ��

11��continue ��

12��

13��

14��

15��