int [] array = {1 , 2 , 3 ,4};boolean cunzai = false;for (int i = 0; i < array.length; i++) {if (array[i] == 3) { //3就是你要判断的数cunzai = true;}}if (cunzai) {System.out.println("存在");}else{System.out.println("不存在");}