null pointer exception in button declaration

in this line am getting NullPointerException can any one help me to fix this

Button up[]; 
up[0] = (Button) findViewById(R.id.adultup1);
up[0].setOnClickListener(new View.OnClickListener() {
    public void onClick(View v开发者_Go百科iew) {}

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You need to allocate the Button array, e.g.

up = new Button[10];