Java Boolean 类的 valueof() 方法返回一个与定义的布尔值或定义的字符串相对应的布尔值实例。
如果定义的布尔值或字符串值为真,则此方法返回布尔值 'true',如果定义的布尔值或字符串值为假,则返回布尔值 'false'。
用法:
public static Boolean valueOf(Boolean b)
public static Boolean valueOf(String s)
参数:
b- 这是一个要传递的布尔参数
s- 这是要传递的字符串参数。
返回值:
valueOf() 方法返回对应于 'b' 或字符串 's' 的布尔实例。
- 如果定义的布尔值 (b) 或字符串值为真,则返回真。
- 如果布尔值 b 为假,则返回假
- 如果字符串包含除 true 以外的任何值,则返回 false。
例子1
public class BooleanValueOfExample1 {
public static void main(String[] args) {
Boolean b1 = true;
// will return a boolean instance corresponding to Boolean b1
Boolean b2 = Boolean.valueOf(b1);
System.out.println("valueOf() method will return = "+b2);
Boolean b3 = Boolean.valueOf(false);
System.out.println("valueOf() method will return = "+b3);
}
}
输出:
valueOf() method will return = true valueOf() method will return = false
例子2
import java.util.Scanner;
public class BooleanValueOfExample2 {
public static void main(String[] args) {
Boolean b1 = true;
Scanner scanner = new Scanner(System.in);
System.out.print("Enter the number whose table you want to print:");
int n =scanner.nextInt();
if(n<0||n>20){
b1 = false;
System.out.println("Please enter a valid number between 0-20.");
}
// will return the boolean value of b1
if(Boolean.valueOf(b1)==true) {
System.out.println("Table of "+n+":");
for (int i = 1; i < 11; i++) {
System.out.println(n +" * "+ i + " = " + n * i);
}
}
}
}
输出:
Enter the number whose table you want to print:19 Table of 19: 19 * 1 = 19 19 * 2 = 38 19 * 3 = 57 19 * 4 = 76 19 * 5 = 95 19 * 6 = 114 19 * 7 = 133 19 * 8 = 152 19 * 9 = 171 19 * 10 = 190
例子3
import java.util.Scanner;
public class BooleanValueOfExample3 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Enter you age");
int a = scanner.nextInt();
if(a>17) {
System.setProperty("flag1", "true");
}
boolean b2 = Boolean.getBoolean("flag1");
if (Boolean.valueOf(b2) == true) {
System.out.println("You are an adult.\nYou are eligible to vote.");
}
else{
int val2 =18-a;
System.out.println("You are not an adult.\nYou will be eligible to vote after "+val2+" years.");
}
}
}
输出:
Enter you age 78 You are an adult. You are eligible to vote.
示例 4
import java.util.Scanner;
public class BooleanValueOfExample4 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("True/False:");
System.out.println("Q. TalMahal is located in Delhi.");
System.out.print("Ans "); String str1 = scanner.next();
// will return boolean value corresponding to the String str
Boolean b1 = Boolean.valueOf(str1);
if (b1 ==true) {
System.out.println("Correct answer.\nAs TajMahal is located in Agra nor in Delhi.");
} else {
System.out.println("Incorrect. Because TajMahal is located in Agra.");
}
}
}
输出:
True/False: Q. TalMahal is located in Delhi. Ans false Incorrect. Because TajMahal is located in Agra.
例 5
public class BooleanValueOfExample5 {
public static void main(String[] args) {
//for "true" (ignoring the case) string value this method will return true.
String str = "True";
Boolean b1 = Boolean.valueOf(str);
System.out.println("1. Boolean value for "+str+" is "+b1);
//for "false" String value this method will return false
String str1= "false";
Boolean b2 = Boolean.valueOf(str1);
System.out.println("2. Boolean value for "+str1+" is "+b2);
//for any String value other than "true" this method will return false.
String str2 = "hwhfjh";
Boolean b3 = Boolean.valueOf(str2);
System.out.println("3. Boolean value for "+str2+" is "+b3);
}
}
输出:
1. Boolean value for True is true 2. Boolean value for false is false 3. Boolean value for hwhfjh is false
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注:本文由纯净天空筛选整理自 Java Boolean valueOf() Method。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。