如何将String转换为int?
"1234" → 1234
如何将String转换为int?
"1234" → 1234
当前回答
对于Android开发者来说,以下是Kotlin的各种解决方案:
// Throws exception if number has bad form
val result1 = "1234".toInt()
// Will be null if number has bad form
val result2 = "1234"
.runCatching(String::toInt)
.getOrNull()
// Will be the given default if number has bad form
val result3 = "1234"
.runCatching(String::toInt)
.getOrDefault(0)
// Will be return of the else block if number has bad form
val result4 = "1234"
.runCatching(String::toInt)
.getOrElse {
// some code
// return an Int
}
其他回答
另一种解决方案是使用Apache Commons的NumberUtils:
int num = NumberUtils.toInt("1234");
Apache实用程序很好,因为如果字符串是无效的数字格式,则始终返回0。因此,节省了try-catch块。
Apache NumberUtils API 3.4版
嗯,需要考虑的一个非常重要的点是Integer解析器抛出了Javadoc中所述的NumberFormatException。
int foo;
String StringThatCouldBeANumberOrNot = "26263Hello"; //will throw exception
String StringThatCouldBeANumberOrNot2 = "26263"; //will not throw exception
try {
foo = Integer.parseInt(StringThatCouldBeANumberOrNot);
} catch (NumberFormatException e) {
//Will Throw exception!
//do something! anything to handle the exception.
}
try {
foo = Integer.parseInt(StringThatCouldBeANumberOrNot2);
} catch (NumberFormatException e) {
//No problem this time, but still it is good practice to care about exceptions.
//Never trust user input :)
//Do something! Anything to handle the exception.
}
在尝试从拆分参数中获取整数值或动态解析某些内容时,处理此异常非常重要。
import java.util.*;
public class strToint {
public static void main(String[] args) {
String str = "123";
byte barr[] = str.getBytes();
System.out.println(Arrays.toString(barr));
int result = 0;
for(int i = 0; i < barr.length; i++) {
//System.out.print(barr[i]+" ");
int ii = barr[i];
char a = (char) ii;
int no = Character.getNumericValue(a);
result = result * 10 + no;
System.out.println(result);
}
System.out.println("result:"+result);
}
}
除了所有这些答案,我发现了一种新的方法,尽管它在内部使用Integer.parseInt()。
通过使用
import javafx.util.converter.IntegerStringConverter;
new IntegerStringConverter().fromString("1234").intValue()
or
new IntegerStringConverter().fromString("1234")
尽管随着新对象的创建,它的成本有点高。
只需浏览javafx.util.StringConverter<T>类。它有助于将任何包装器类值转换为字符串,反之亦然。
您只需尝试以下操作:
使用Integer.parseInt(your_string);将字符串转换为int使用Double.parseDouble(your_string);将字符串转换为double
实例
String str = "8955";
int q = Integer.parseInt(str);
System.out.println("Output>>> " + q); // Output: 8955
String str = "89.55";
double q = Double.parseDouble(str);
System.out.println("Output>>> " + q); // Output: 89.55