- 两数相加
源文件：Addition.java
源代码：
// An addition program
import javax.swing.JOptionPane; // import class JOptionPane
public class Addition {
public static void main( String args[] )
{
String firstNumber, // first string entered by user
secondNumber; // second string entered by user
int number1, // first number to add
number2, // second number to add
sum; // sum of number1 and number2
// read in first number from user as a string
firstNumber =
JOptionPane.showInputDialog( "Enter first integer" );
// read in second number from user as a string
secondNumber =
JOptionPane.showInputDialog( "Enter second integer" );
// convert numbers from type String to type int
number1 = Integer.parseInt( firstNumber );
number2 = Integer.parseInt( secondNumber );
// add the numbers
sum = number1 + number2;
// display the results
JOptionPane.showMessageDialog(
null, "The sum is " + sum, "Results",
JOptionPane.PLAIN_MESSAGE );
System.exit( 0 ); // terminate the program
}
}
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- 枚举
源文件：EnumText.java
源代码：
public class EnumTest {
public static void main(String[] args) {
Size s=Size.SMALL;
Size t=Size.LARGE;
//s和t引用同一个对象？
System.out.println(s==t); //
//是原始数据类型吗？
System.out.println(s.getClass().isPrimitive());
//从字符串中转换
Size u=Size.valueOf("SMALL");
System.out.println(s==u); //true
//列出它的所有值
for(Size value:Size.values()){
System.out.println(value);
}
}
}
enum Size{SMALL,MEDIUM,LARGE};
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- 读取输入
源文件InputTest.java
源代码
import java.util.*;
public class InputTest
{
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
// get first input
System.out.print("What is your name? ");
String name = in.nextLine();
// get second input
System.out.print("How old are you? ");
int age = in.nextInt();
/* int i;
String value="100";
i=Integer.parseInt(value);
i=200;
String s=String.valueOf(i);*/
// display output on console
System.out.println("Hello, " + name + ". Next year, you'll be " + (age + 1));
}
}
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4double类型.
源文件 TestDouble.java
源代码
public class TestDouble {
public static void main(String args[]) {
System.out.println("0.05 + 0.01 = " + (0.05 + 0.01));
System.out.println("1.0 - 0.42 = " + (1.0 - 0.42));
System.out.println("4.015 * 100 = " + (4.015 * 100));
System.out.println("123.3 / 100 = " + (123.3 / 100));
}
}
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