How to convert string to number in java

Java string to number method: 1. Convert to integer number [Integer.parseInt(String s)]; 2. Convert to floating point number [Float.parseFloat(String s)].

Related free learning recommendations: java basic tutorial

java string Method of converting numbers:

1. Convert to integer numbers

(1) Integer.parseInt(String s), the code example is as follows:

public class Test {
public static void main(String args[]){
String s = "123";
int num = Integer.parseInt(str);
int sum = num + 100;
System.out.println("Result is: "+sum); // 输出结果为：Result is: 223
}}

(2) Integer.valueOf(String s), the code example is as follows:

public class Test2 {
public static void main(String args[]){
String s = "-100";
int num = Integer.valueOf(str);
int sum = num + 101;
System.out.println("Result is: "+sum); // 输出结果为：Result is: 1
} }

2, Convert to floating point number

(1) Float.parseFloat(String s), the code example is as follows:

public class Test {
public static void main(String args[]){
String s = "123.11";
float num = Float.parseFloat(s);
float sum = num + 100;
System.out.println("Result is: "+sum); // 输出结果为：Result is: 223.11
}}

(2) Double .parseDouble(String s), the code example is as follows:

public class Test2 {
public static void main(String args[]){
String s = "100.01";
double num = Double.parseDouble(s);
double sum = num + 100;
System.out.println("Result is: "+sum); // 输出结果为：Result is: 200.01
}}

The specific code required in the question to convert String s="00000123" into 123 is as follows:

public class Test {
public static void main(String args[]){
String s = "00000123";
int num =  Integer.parseInt(s);
System.out.println("Result is: "+num); // 输出结果为：Result is: 123
}}

Extended information:

1. Convert integer and floating point types to strings in Java:

public class Test {
public static void main(String args[]){
int i = 11;
String s = i + ""; // 方法一
String s = String.valueOf(i); // 方法二
String s = Integer.toString(i); // 方法三
} }

2. Determine whether a string is a number in Java:

public static boolean isNumeric(String str){
for (int i = str.length();--i>=0;){
if (!Character.isDigit(str.charAt(i))){
return false;
} }
return true;
}

The above is the detailed content of How to convert string to number in java. For more information, please follow other related articles on the PHP Chinese website!