追加得字符串不显示在System.Out.Println

Question

import java.io.BufferedWriter;
import java.io.FileWriter;

public class RandomNumber {

    public static void main(String[] args) {

    try {

        int n = 10000;
        String line = ""; // Have tried StringBuilder too, doesn't help
        for (int i = 0; i < n; i++) {
            int temp = (int) Math.ceil((Math.random() * n));
            line = line+temp+" ";
            System.out.println(line);
        }
        FileWriter fstream = new FileWriter("input" + n + ".txt");
        BufferedWriter out = new BufferedWriter(fstream);
        out.write(line);
        out.close();
    } catch (Exception e) {
        System.err.println("Error: " + e.getMessage());
    }
    }
}

编辑：我已经删除了用于out.write的for循环，它不是必需的。我在使用字符串数组时使用过它。

Answer 1

试试这个

import java.io.BufferedWriter;
import java.io.FileWriter;

public class RandomNumber {

    public static void main(String[] args) {

    try {

        int n = 10000;
        String line = "";
        for (int i = 0; i < n; i++) {
            int temp = (int) Math.ceil((Math.random() * n));
            line = line+temp+" ";
            System.out.println(line);
        }

        System.out.println("file name is :: input" + n + ".txt");
        FileWriter fstream = new FileWriter("input" + n + ".txt");
        BufferedWriter out = new BufferedWriter(fstream);
        // till here you were correct.
        // you don't need the loop here...
        out.write(line);
        out.close();
    } catch (Exception e) {
        System.err.println("Error: " + e.getMessage());
    }
    }
}

也看一下这里。

由于您的程序可以很好地处理n=10、n=100、n=1000，我建议您增加Eclipse中的堆大小。