凝輝部落格

1.
class ch07_5 {
 public static void main(String [] args) {
  int[] ori = {5, 2, 0, 7, 8, 9};
  int[] dup, dup1;// 參照
       
        dup1=ori; // 參照
  dup = duplicateArray(ori); dup[2]=100; dup1[3]=200; ori[4]=45;
  System.out.println("dup: " + dup1); showArr(dup1);
  System.out.println("ori: " + ori); showArr(ori);
  System.out.println("dup: " + dup); showArr(dup);
 }

 static int[] duplicateArray(int[] a) {
  int[] b = new int[a.length];
  for(int i=0; i   return b;
 }

 static void showArr(int[] a) {
  for(int i=0; i   System.out.print("\n");
 }
}

2.
class ch07_6 {
 int a=10;
    short c=3;
   
 public static void main(String [] args) {
  ch07_6 obj = new ch07_6();
  obj.myMethod(1);
  
  int a=20; obj.mm(a); System.out.println("obj: a="+a);
 }
    static void mm(int a) { a*=a; }
    void myMethod(int a) { 
       
  System.out.println("方法內 this.a:" + this.a); //10
  int c=30;

  {
   {
    int b=2;
    System.out.println("巢狀區塊內 b:" + b);//2
    System.out.println("巢狀區塊內 this.b:" + this.b);//2
   }
   System.out.println("區塊內 b:" + b);//2
   System.out.println("區塊內 this.b:" + this.b);//2
  }
  System.out.println("區塊內 c:" + c);//30
  System.out.println("區塊內 this.c:" + this.c);//3
 }
 
 
 public void method() {
  int c;
  int d=5;
  
  a++; b++;  this.c++;
  System.out.println("a="+a);
  System.out.println("b="+b);
  System.out.println("c="+this.c);
  System.out.println("d="+d);
 }
 
 static int b = 2; 
}
3.
public class ch07_007 {
 public static int m=1000;
 public static void main(String[] args){
  int n=m++;
  System.out.println(m);
  System.out.println(n);
 
 }
}

4.
import java.io.*;
import javax.swing.*;
class ch07_7 {
  public static void main(String [] args) throws IOException {
    FileReader fr=new FileReader("a1.txt");  // read file
    BufferedReader br=new BufferedReader(fr);
    int n=0;
   
    String str=br.readLine();
    if (str != null) n=Integer.parseInt(str);
    System.out.println(n + "!=" + fact(n) );
    System.out.println("F("+n + ")=" + f(n) );
    str=JOptionPane.showInputDialog( "Enter first integer" );
    if (str != null) n=Integer.parseInt(str);
    System.out.println(n + "!=" + fact(n) );
    System.out.println("F("+n + ")=" + f(n) );
  }

  static long fact(int n) { //factorial
 if(n==1) return 1;
 else return n*fact(n-1);
  }
  static int f(int n) { //fibonacci
   if ((n==1) || (n==2)) return 1;
   else return f(n-1)+f(n-2);
  }
}

5.
class ch07_0021{
 int i=10;
 public static void main(String args[]) {
   ch07_0021 t=new ch07_0021();
   t.m1(); 
 }
 void m1() {
   int i=20;
   ch07_0021 t=new ch07_0021();
   t.i=30;
   m2(t,i);
   System.out.println(t.i);
 }
 void m2(ch07_0021 t,int i) {
   i=0;
   t.i=40;
   ch07_0021 d=new ch07_0021();
   t=d;
   System.out.print(t.i+","+i+",");
 }
}
6.
class ch07_8 {
 public static void main(String [] args) {
  new Box(6);
  new Box(5, 4, 3);
  new Box(); //error!!!
 }
}

class Box {
 int height; 
 int width; 
 int thickness; 
 
 public Box() {
   height=width=100 ; thickness=10;
   int i = height*width*thickness;
   System.out.println(this + "的體積為:" + i);
 }
 public Box(int n) {//constructor
     this();
  height = width = thickness = n;
     int i = height*width*thickness;
  System.out.println(this + "的體積為:" + i);
 }

 public Box(int height, int width, int thickness) {
  this();
  this.height = height; 
  this.width = width;
  this.thickness = thickness;
        int i = height*width*thickness;
  System.out.println(this + "的體積為:" + i);
 }

/* void Box() { // method
  int i = height*width*thickness;
  System.out.println(this + "的體積為:" + i);
 } */
}
7.
public class ch07_009 {
 public static void main(String [] args){}
 public void myTest(int i){}
 
 //A public long myTest(int a){return 168;}
  public boolean myTest(){return false;}//B
 //C private long myTest(int i){return 99;}
  public void main(int i){}//D
 //E int main(String s[]){return 1;}
}
8.
9.
public class ch07_0013{
 private static int x=7;
 ch07_0013(int n){
  x=n;
 }
 
 public static void main(String [] args){
  ch07_0013 t=new ch07_0013(6);
  System.out.println(t.x);
  
 }
}