Java – why must the float value be declared twice?

I'm confused why floating point values must be declared as in any other value, but they must be declared before the value

Example: floating point z = (floating point) 10.5;

Why can't we declare floating point values as;

Example: floating point number Z = 10.5;

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Solution

Because 10.5 is a double, it cannot be implicitly converted to floating

Float z = 10.5f;