Question

EditText numDisplay;
Button calculateNow;
int n=100;
int count=0;
List<Integer> primes = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    numDisplay= (EditText)findViewById(R.id.editText1);
    n= Integer.parseInt(numDisplay.toString());
    calculateNow = (Button)findViewById(R.id.button1);
    calculateNow.setOnClickListener(new Button.OnClickListener() {
        public void onClick(View v) {
            for (int i = 2; i < n; i++) {
                boolean res = checkprime(primes, i);
                if (res) {
                    count++;
                    primes.add(i);
                }
            }
          numDisplay.setText( String.valueOf(count));
          // writer.write("total prime number till " + n + " is " + count);
        }});}

private static boolean checkprime(List<Integer> primes, int n) {
    int fence = (int) Math.sqrt(n);
    for (int prime : primes) {
        if (n % prime == 0) {
            return false;
        }
        if (prime >= fence)
            break;
    }

    return true;
}

程序的输出必须打印从1到100的素数总数。

单击按钮时，我使用编辑文本显示素数的总数。

但是当我点击按钮时，我没有得到所需的输出。任何帮助表示赞赏。感谢名单

Answer 1

更新您的： -

public class AnimationActivity extends ActionBarActivity {
EditText numDisplay;
Button calculateNow;
private int n;
int count=0;
List<Integer> primes = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    numDisplay= (EditText)findViewById(R.id.editText1);
    calculateNow = (Button)findViewById(R.id.button1);

    calculateNow.setOnClickListener(new Button.OnClickListener() {

        public void onClick(View v) {
            n= Integer.parseInt(numDisplay.getText().toString());
            for (int i = 2; i < n; i++) {
                boolean res = checkprime(primes, i);
                if (res) {
                    count++;
                    primes.add(i);
                }
            }
            numDisplay.setText(String.valueOf(count));

        }
    });}

private static boolean checkprime(List<Integer> primes, int n) {
    int fence = (int) Math.sqrt(n);
    for (int prime : primes) {
        if (n % prime == 0) {
            return false;
        }
        if (prime >= fence)
            break;
    }

    return true;
}}

没有得到Android应用程序的所需输出

1 个答案: