JAVA学习二

一、控制流程

块的作用:(块)是指由一对花括号括起来的若干java语句。块确定了JAVA的作用域。

public static void main(String[] args)

{

  int n;

  ...

  {

    int k;

  }//k is only defined up to here 

}

 

比如下列声明就是错误的:

public static void main(String[] args)

{

  int n;

  ...

  {

    int k;

    int n;//ERROR-can't redefine in inner blcok

  }

}

 

二、循环

 

package demo10;

import java.io.Console;
import java.util.*;

public class java1
{
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.println("How much money do you need to retire?");

double goal = in.nextDouble();

System.out.println("How much money will you contribute every day?");

double payment = in.nextDouble();

System.out.println("Interest rate in %");

double interestRate = in.nextDouble();

double balance = 0;
int years = 0;

while(balance<goal)
{
balance+=payment;
double interest = balance * interestRate/100;
balance += interest;
years++;

}

System.out.println("You can retire in" + years +"years");



}


}

}


 

三、多重选择:SWITCH语句

Scanner in = new Scanner(System.in);
System.out.println("Select option(1,2,3,4)");
int choice = in.nextInt();
switch(choice)
{
  case 1:
    ///
    break;
  case 2:
    ///
    break;
  case 3:
    ///
    break;
  default:
    //bad input
    break;
}


switch 语句将从与选项值相匹配的 case 标签处开始执行直到

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