Java convert any integer to 4 digits

String a = String.format("%04d", 31200).substring(0, 4);
/**Output: 3120 */ 
System.out.println(a);


String b = String.format("%04d", 8).substring(0, 4);
/**Output: 0008 */
System.out.println(b);

As simple as that:

String.format("%04d", 300)

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For comparing hours before minutes:

int time1 =  350;
int time2 = 1210;
//
int hour1 = time1 / 100;
int hour2 = time2 / 100;
int comparationResult = Integer.compare(hour1, hour2);
if (comparationResult == 0) {
    int min1 = time1 % 100;
    int min2 = time2 % 100;
    comparationResult = Integer.compare(min1, min2);
}

Note:

Integer.compare(i1, i2) has been added in Java 1.7, for previous version you can either use Integer.valueOf(i1).compareTo(i2) or

int comparationResult;
if (i1 > i2) {
    comparationResult = 1;
} else if (i1 == i2) {
    comparationResult = 0;
} else {
    comparationResult = -1;
}