如何将String转换为int?
"1234" → 1234
如何将String转换为int?
"1234" → 1234
当前回答
一个方法是parseInt(String)。它返回一个基元int:
String number = "10";
int result = Integer.parseInt(number);
System.out.println(result);
第二个方法是valueOf(String),它返回一个新的Integer()对象:
String number = "10";
Integer result = Integer.valueOf(number);
System.out.println(result);
其他回答
对于普通字符串,可以使用:
int number = Integer.parseInt("1234");
对于字符串生成器和字符串缓冲区,可以使用:
Integer.parseInt(myBuilderOrBuffer.toString());
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);
}
}
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
}
可以通过七种方式实现:
import com.google.common.primitives.Ints;
import org.apache.commons.lang.math.NumberUtils;
String number = "999";
Ints.tryParse:int result=Ints.tryParse(数字);NumberUtils.createInteger:整数结果=NumberUtils.createInteger(数字);应用到内部的数字:int result=NumberUtils.toInt(数字);整数值:整数结果=Integer.valueOf(数字);整数.分析整数:int result=Integer.parseInt(数字);整数代码:int result=Integer.decode(数字);整数.分析未签名:int result=Integer.parseUnsignedInt(数字);
除了前面的答案,我还想添加几个功能。以下是使用时的结果:
public static void main(String[] args) {
System.out.println(parseIntOrDefault("123", 0)); // 123
System.out.println(parseIntOrDefault("aaa", 0)); // 0
System.out.println(parseIntOrDefault("aaa456", 3, 0)); // 456
System.out.println(parseIntOrDefault("aaa789bbb", 3, 6, 0)); // 789
}
实施:
public static int parseIntOrDefault(String value, int defaultValue) {
int result = defaultValue;
try {
result = Integer.parseInt(value);
}
catch (Exception e) {
}
return result;
}
public static int parseIntOrDefault(String value, int beginIndex, int defaultValue) {
int result = defaultValue;
try {
String stringValue = value.substring(beginIndex);
result = Integer.parseInt(stringValue);
}
catch (Exception e) {
}
return result;
}
public static int parseIntOrDefault(String value, int beginIndex, int endIndex, int defaultValue) {
int result = defaultValue;
try {
String stringValue = value.substring(beginIndex, endIndex);
result = Integer.parseInt(stringValue);
}
catch (Exception e) {
}
return result;
}