Integer is a simple one, but it's a little different. Integer is a wrapper class of int, which can play the role of caching. In the java foundation, it said that its range is (- 128-127). In this return, there is a cache, and no new integer object will be created, and its maximum value can be set by setting VM parameters.

Let's take a look at the source code:

 public static Integer valueOf(int i) {
        if(i >= -128 && i <= IntegerCache.high)
            return IntegerCache.cache[i + 128];
        else
            return new Integer(i);
    }

private static class IntegerCache {
        static final int high;
        static final Integer cache[];

        static {
            final int low = -128;

            // high value may be configured by property
            int h = 127;
            if (integerCacheHighPropValue != null) {
                // Use Long.decode here to avoid invoking methods that
                // require Integer's autoboxing cache to be initialized
                int i = Long.decode(integerCacheHighPropValue).intValue();
                i = Math.max(i, 127);
                // Maximum array size is Integer.MAX_VALUE
                h = Math.min(i, Integer.MAX_VALUE - -low);
            }
            high = h;

            cache = new Integer[(high - low) + 1];
            int j = low;
            for(int k = 0; k < cache.length; k++)
                cache[k] = new Integer(j++);
        }

        private IntegerCache() {}
    }

// value of java.lang.Integer.IntegerCache.high property (obtained during VM init)
    private static String integerCacheHighPropValue;
    static void getAndRemoveCacheProperties() {
        if (!sun.misc.VM.isBooted()) {
            Properties props = System.getProperties();
            integerCacheHighPropValue =
                (String)props.remove("java.lang.Integer.IntegerCache.high");
            if (integerCacheHighPropValue != null)
                System.setProperties(props);  // remove from system props
        }
    }

You can adjust the maximum value of VM by setting its java.lang.Integer.IntegerCache.high. Although it is a constant in a static code block, it is assigned during initialization, so it has no impact.

Demonstrate modifying JVM parameters (eclipse):

package test1;

public class Demo1 {
    
    public static void main(String[] args) {
        System.out.println(Integer.valueOf(200)==Integer.valueOf(200));
    }

}

Output results:

false

How to modify it? Look at the following?

Click the project you created, right-click - > debug as - > debug configurations - > java application - > click your own project - > arguments - > VM arguments settings - > apply - > debug

Set later results: