JAVA 基礎入門課本例題代碼(第二章)-有解無憂

JAVA 基礎入門課本例題代碼(第二章)

Example01

public class Example01 {
	
	public static void main (String[] ags)
	{
		int num=4;
		byte b=(byte)num;
		System.out.println(b);
	}
	
}

Example02

public class Example02 {
	
	public static void main (String[] ags)
	{
		byte a;
		int b=298;
		a=(byte)b;
		System.out.println("a="+a);
		System.out.println("b="+b);
	}
	
}

Example03

public class Example03 {
	
	public static void main (String[] ags)
	{
		byte a=1;
		byte b=2;
		byte c=(byte)(a+b);
		
		System.out.println("c="+c);
	}
	
}

Example04

public class Example04 {
	
	public static void main (String[] ags)
	{
		int a=12;
		{
			int b=13;
			System.out.println("a="+a);
			System.out.println("b="+b);
		}
		//b=a;
		System.out.println("a="+a);
		//System.out.println("b="+b);
	}
	
}

Example05

public class Example05 {
	
	public static void main (String[] ags)
	{
		short s=1;
		int a=10;
		s+=a;
		System.out.println("s="+s);
	}
	
}

Example06

public class Example06 {
	
	public static void main (String[] ags)
	{
		int a,b,c;
		a=b=c=0;
		boolean x,y;
		x=a>0&b++>1;
		System.out.println(x);
		System.out.println("b="+b);
		y=a>0&&c++>1;
		System.out.println(y);
		System.out.println("c="+c);
	}
	
}

Example07

public class Example07 {
	
	public static void main (String[] ags)
	{
		int x=5;
		if(x<10){
			x++;
		}
		System.out.println("x="+x);
	}
	
}

Example08

public class Example08 {
	
	public static void main (String[] ags)
	{
		int num=19;
		if(num%2==0){
		System.out.println("這是一個偶數");		
		}
		else{
			System.out.println("這是一個奇數");
		}
	}
	
}

Example09

public class Example09 {
	
	public static void main (String[] ags)
	{
		int great=75;
		if(great>80){
			System.out.println("該成績的登級為優等");	
		}
		else if(great>70){
			System.out.println("該成績的登級為良");	
		}
		else if (great>60){
			System.out.println("該成績的登級為中");	
		}
		else{
			System.out.println("該成績的登級為差");	
		}
	}
	
}

Example10

public class Example10 {
	
	public static void main (String[] ags)
	{
		int week=5;
		switch (week){
			case 1:
				System.out.println("星期一");
				break;
			case 2:
				System.out.println("星期二");
				break;
			case 3:
				System.out.println("星期三");
				break;
			case 4:
				System.out.println("星期四");
				break;
			case 5:
				System.out.println("星期五");
				break;
			case 6:
				System.out.println("星期六");
				break;
			case 7:
				System.out.println("星期天");
				break;
			default:
				System.out.println("輸入的數字不正確.....");
		}
	}
	
}

Example11

public class Example11 {
	
	public static void main (String[] ags)
	{
		int week=2;
		switch (week){
			case 1:
				
			case 2:
				
			case 3:
				
			case 4:
				
			case 5:
				System.out.println("今天是作業日");
				break;
			case 6:
				
			case 7:
				System.out.println("今天是休息日");
				break;
			default:
				System.out.println("輸入的數字不正確.....");
		}
	}
	
}

Example12

public class Example12 {
	
	public static void main (String[] ags)
	{
		int x=1;
		while (x<=4){
			System.out.println("x="+x);
			x++;
		}
	}
	
}

Example13

public class Example13 {
	
	public static void main (String[] ags)
	{
		int x=1;
		do{
			System.out.println("x="+x);
			x++;
		}while (x<=4);
	}
	
}

Example14

public class Example14 {
	
	public static void main (String[] ags)
	{
		int sum=0;
		for(int i=1;i<=4;i++){
			sum+=i;
		}
		System.out.println("sum="+sum);
	}
	
}

Example15

public class Example15 {
	
	public static void main (String[] ags)
	{
		int i,j;
		for(i=1;i<=9;i++){
			for(j=1;j<=i;j++){
			System.out.print("*");
		}
			System.out.print("\n");
		}
	}		
}

Example16

public class Example16 {
	
	public static void main (String[] ags)
	{
		int x=1;
		while (x<=4){
			System.out.println("x="+x);
				if(x==3){
					break;
				}
			x++;
		}
	}
	
}

Example17

public class Example17 {
	
	public static void main (String[] ags)
	{
		int i,j;
		itcast:for(i=0;i<9;i++){
			for(j=0;j<i;j++){
				if(i==3)
					break itcast;
				System.out.print("*");
			}
			System.out.print("\n");
			
		}
		
	}
	
}

Example18

public class Example18 {
	
	public static void main (String[] ags)
	{
		int sum=0;
		int i;
		for(i=1;i<=100;i++){
			if(i%2==0)
				continue;
			sum+=i;
		}
		System.out.println("sum="+sum);
	}
	
}

Example19

public class Example19 {
	
	public static void main (String[] ags)
	{
		for(int i=0;i<3;i++){
			for(int j=0;j<5;j++){
				System.out.print("*");
			}
			System.out.print("\n");
		}
		System.out.print("\n");
	
		for(int i=0;i<2;i++){
			for(int j=0;j<4;j++){
				System.out.print("*");
			}
			System.out.print("\n");
		}
		System.out.print("\n");
	
		for(int i=0;i<6;i++){
			for(int j=0;j<10;j++){
				System.out.print("*");
			}
			System.out.print("\n");
		}
		System.out.print("\n");
	}
	
}

Example20

public class Example20 {
	
	public static void main (String[] ags)
	{
		printRectaing(3,5);
		printRectaing(2,4);
		printRectaing(6,10);
	}
	public static void printRectaing(int height,int width){
		for(int i=0;i<height;i++){
			for(int j=0;j<width;j++){
			System.out.print("*");	
			}
			System.out.print("\n");
		}	
		System.out.print("\n");
	}
}

Example21

public class Example21 {
	
	public static void main (String[] ags)
	{
		int area=getAear(3,5);
		System.out.println("There area is "+area);
		}
		public static int getAear(int i,int j){
			return i*j;
		}
	
}

Example22

public class Example22 {
	
	public static void main (String[] ags)
	{
		int sum01=add01(1,2);
		int sum02=add02(1,2,3);
		double sum03=add03(1.2,2.3);
		System.out.println("sum01="+sum01);
		System.out.println("sum02="+sum02);
		System.out.println("sum03="+sum03);
	}
	public static int add01(int x,int y){
		return  x+y;
	}
	public static int add02(int x,int y,int z){
		return x+y+z;
	}
	public static double add03(double x,double y){
		return x+y;
	}
}

Example23

public class Example23 {
	
	public static void main (String[] ags)
	{
		int sum01=add(1,2);
		int sum02=add(1,2,3);
		double sum03=add(1.2,2.3);
		System.out.println("sum01="+sum01);
		System.out.println("sum02="+sum02);
		System.out.println("sum03="+sum03);
	}
	public static int add(int x,int y){
		return x+y;
	}
	public static int add(int x,int y,int z){
		return x+y+z;
	}
	public static double add(double	x,double y){
		return x+y;
	}
}

Example24

public class Example24 {
	
	public static void main (String[] ags)
	{
		int sum=getSum(4);
		System.out.println("sum="+sum);
	}
	public static int getSum(int n){
		if(n==1){
			return 1;
		}
		else {
			int temp=getSum(n-1);
			return temp+n;
		}
	}
}

Example25

public class Example25 {
	
	public static void main (String[] ags)
	{
		int[]arr;
		arr=new int[4];
		System.out.println("arr[0]="+arr[0]);
		System.out.println("arr[1]="+arr[1]);
		System.out.println("arr[2]="+arr[2]);
		System.out.println("arr[3]="+arr[3]);
	}
	
}

Example26

public class Example26 {
	
	public static void main (String[] ags)
	{
		int []arr= new int [4];
		arr[0]=1;
		arr[1]=2;
		System.out.println("arr[0]="+arr[0]);
		System.out.println("arr[1]="+arr[1]);
		System.out.println("arr[2]="+arr[2]);
		System.out.println("arr[3]="+arr[3]);
	}
	
}

Example27

public class Example27 {
	
	public static void main (String[] ags)
	{
		int[]arr={1,2,3,4};
		System.out.println("arr[0]="+arr[0]);
		System.out.println("arr[1]="+arr[1]);
		System.out.println("arr[2]="+arr[2]);
		System.out.println("arr[3]="+arr[3]);
	}
	
}

Example28

public class Example28 {
	
	public static void main (String[] ags)
	{
		int []arr=new int [4];
		
		System.out.println("arr[3]="+arr[3]);
		//System.out.println("a[4]="+a[4]);
	}
	
}
/**

這部分代碼是為了驗證陣列的角標是從0開始的，四個陣列元素即是arr[0]到arr[3]

*/

Example29

public class Example29 {
	
	public static void main (String[] ags)
	{
		int []arr=new int [2];
		System.out.println("arr[0]="+arr[0]);
		System.out.println("arr[1]="+arr[1]);
		arr=null;
		System.out.println("arr[0]="+arr[0]);
		System.out.println("arr[1]="+arr[1]);
	}
	
}

Example30

public class Example30 {
	
	public static void main (String[] ags)
	{
		int[]arr={1,2,3,4};
		for(int i=0;i<arr.length;i++){
			System.out.println(arr[i]);
		}
		
	}
	
}

Example31

public class Example31 {
	
	public static void main (String[] ags)
	{
		int []arr={8,4,3,5,7,3};
		int max=getMax(arr);
		System.out.println(max);
	}
	 static int getMax(int []arr){
		int max=arr[0];
		for(int i=1;i<arr.length;i++){
			if(max<arr[i])
				max=arr[i];
		}
	
	return max;
	 }
}

Example32

public class Example32 {
	
	public static void main (String[] ags)
	{
		int []arr={9,8,3,5,2};
		System.out.print("冒泡排序前：");
		printArray(arr);
		bubbleSort(arr);
		System.out.println("冒泡排序后：");
		printArray(arr);
	}
	public static void printArray (int []arr){
		for(int i=0;i<arr.length;i++){
			System.out.print(arr[i]+" ");//數字后面加一個空格
		}
		System.out.print("\n");
	}
	public static void bubbleSort (int []arr){
		for(int i=0;i<arr.length-1;i++){
			for(int j=0;j<arr.length-i-1;j++){
				if(arr[i]>arr[i+1]){
				int temp=arr[j];
				arr[j]=arr[j+1];
				arr[j+1]=temp;
				}
			}
			System.out.printf("第"+(i+1)+"輪排序后：");
			printArray(arr);
		}
	}
}

Example33

public class Example33 {
	
	public static void main (String[] ags)
	{
		int [][]arr=new int [3][];
		arr[0]=new int []{11,12};
		arr[1]=new int []{21,22,23};
		arr[2]=new int []{31,32,33,34};
		int sum=0;
		for(int i=0;i<arr.length;i++){
			int groupSum=0;
			for(int j=0;j<arr[i].length;j++){
				groupSum=groupSum+arr[i][j];
			}
			sum+=groupSum;
			System.out.println("第"+(i+1)+"小組銷售額為："+groupSum+"萬元");
		}
		System.out.println("總銷售額為："+sum+"萬元");
	}
	
}

轉載請註明出處，本文鏈接：https://www.uj5u.com/ruanti/137953.html

標籤：其他

上一篇：libevent的兩個服務端、客戶端示例（C語言）

下一篇：Android音樂播放器