Convert String to int, long, float and double in Java



Write a Java program that converts the given string (representing a number) to an intlongfloat, and double.

Java program for String Conversion

public class Main {

    private static final String TO_INT = "453";
    private static final String TO_LONG = "45234223233";
    private static final String TO_FLOAT = "45.823F";
    private static final String TO_DOUBLE = "13.83423D";

    private static final String TO_INT_NEGATIVE = "-453";
    private static final String TO_LONG_NEGATIVE = "-45234223233";
    private static final String TO_FLOAT_NEGATIVE = "-45.823F";
    private static final String TO_DOUBLE_NEGATIVE = "-13.83423D";

    public static void main(String[] args) {

        // convert String to int/Integer
        Integer toInt1 = Integer.valueOf(TO_INT);                          // returns Integer
        int toInt2 = Integer.parseInt(TO_INT);                             // returns int
        Integer toIntNegative1 = Integer.valueOf(TO_INT_NEGATIVE);         // returns Integer
        int toIntNegative2 = Integer.parseInt(TO_INT_NEGATIVE);            // returns int

        // convert String to long/Long
        Long toLong1 = Long.valueOf(TO_LONG);                              // returns Long
        long toLong2 = Long.parseLong(TO_LONG);                            // returns long
        Long toLongNegative1 = Long.valueOf(TO_LONG_NEGATIVE);             // returns Long
        long toLongNegative2 = Long.parseLong(TO_LONG_NEGATIVE);           // returns long

        // convert String to float/Float
        Float toFloat1 = Float.valueOf(TO_FLOAT);                          // returns Float
        float toFloat2 = Float.parseFloat(TO_FLOAT);                       // returns float
        Float toFloatNegative1 = Float.valueOf(TO_FLOAT_NEGATIVE);         // returns Float
        float toFloatNegative2 = Float.parseFloat(TO_FLOAT_NEGATIVE);      // returns float

        // convert String to double/Double
        Double toDouble1 = Double.valueOf(TO_DOUBLE);                      // returns Double
        double toDouble2 = Double.parseDouble(TO_DOUBLE);                  // returns double
        Double toDoubleNegative1 = Double.valueOf(TO_DOUBLE_NEGATIVE);     // returns Double
        double toDoubleNegative2 = Double.parseDouble(TO_DOUBLE_NEGATIVE); // returns double

        System.out.println("\"" + TO_INT + "\"" + " as int is "
                + toInt1 + " and as Integer is " + toInt2);
        System.out.println("\"" + TO_INT_NEGATIVE + "\"" + " as int is "
                + toIntNegative1 + " and as Integer is " + toIntNegative2);

        System.out.println("\"" + TO_LONG + "\"" + " as long is "
                + toLong1 + " and as Long is " + toLong2);
        System.out.println("\"" + TO_LONG_NEGATIVE + "\"" + " as long is "
                + toLongNegative1 + " and as Long is " + toLongNegative2);

        System.out.println("\"" + TO_FLOAT + "\"" + " as float is "
                + toFloat1 + " and as Float is " + toFloat2);
        System.out.println("\"" + TO_FLOAT_NEGATIVE + "\"" + " as float is "
                + toFloatNegative1 + " and as Float is " + toFloatNegative2);

        System.out.println("\"" + TO_DOUBLE + "\"" + " as double is "
                + toDouble1 + " and as Double is " + toDouble2);
        System.out.println("\"" + TO_DOUBLE_NEGATIVE + "\"" + " as double is "
                + toDoubleNegative1 + " and as Double is " + toDoubleNegative2);

    }
}

Output:

"453" as int is 453 and as Integer is 453
"-453" as int is -453 and as Integer is -453
"45234223233" as long is 45234223233 and as Long is 45234223233
"-45234223233" as long is -45234223233 and as Long is -45234223233
"45.823F" as float is 45.823 and as Float is 45.823
"-45.823F" as float is -45.823 and as Float is -45.823
"13.83423D" as double is 13.83423 and as Double is 13.83423
"-13.83423D" as double is -13.83423 and as Double is -13.83423

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