消除double类型计算出现精度损失的方法
package BigDecimalTest; import java.math.BigDecimal; public class TestBigDecimal { public static void main(String[] args) { BigDecimal f1 = new BigDecimal("0.05"); BigDecimal f2 = BigDecimal.valueOf(0.01); BigDecimal f3 = new BigDecimal(0.05); System.out.println("下面使用String作为BigDecimal构造器参数的计算结果:"); System.out.println("0.05 + 0.01 = " + f1.add(f2)); System.out.println("0.05 - 0.01 = " + f1.subtract(f2)); System.out.println("0.05 * 0.01 = " + f1.multiply(f2)); System.out.println("0.05 / 0.01 = " + f1.divide(f2)); System.out.println("下面使用double作为BigDecimal构造器参数的计算结果:"); System.out.println("0.05 + 0.01 = " + f3.add(f2)); System.out.println("0.05 - 0.01 = " + f3.subtract(f2)); System.out.println("0.05 * 0.01 = " + f3.multiply(f2)); System.out.println("0.05 / 0.01 = " + f3.divide(f2)); } }
value()可以将小括号内的内容转为字符串类型
package Doubletest; 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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生成界面实现两数相加输出
package AdditionTest; // 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 } }