Question

我正在尝试创建一个最终发送到数据库的密码生成器（随机字符串生成器），但是当我在一个活动中使用下面的代码时，应用程序终止时出现错误“java.lang.ArrayIndexOutOfBoundsException：length = 67; index = 85“此代码应使用循环从字符数组中返回一个随机值以生成字符串。

package com.example.zakratcliffe.androidantitheft;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import java.util.Random;

public class ProfileActivity extends AppCompatActivity {


private TextView textViewUsername, textViewUserEmail;
private EditText textEditDescription, textEditPassword;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_profile);

    if (!SharedPrefManager.getInstance(this).isLoggedIn()) {
        finish();
        startActivity(new Intent(this, LoginActivity.class));
    }

    textViewUsername = (TextView) findViewById(R.id.textViewUsername);
    textViewUserEmail = (TextView) findViewById(R.id.textViewUseremail);
    textEditDescription = (EditText) findViewById(R.id.editTextDescription);
    textEditPassword = (EditText) findViewById(R.id.editTextPassword);

    textViewUserEmail.setText(SharedPrefManager.getInstance(this).getUserEmail());
    textViewUsername.setText(SharedPrefManager.getInstance(this).getUsername());

    final Button button = (Button) findViewById(R.id.generate_button);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String pass = Generated_pass();
            textEditPassword.setText(pass);
        }
    });
}

String Generated_pass(){
    char[] GenPass = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '@', '!', '?', '&', '%', '~'};
    int i = 1;
    String GeneratedPass = "";
    while (i < 13){
        Random r = new Random();
        int Character = r.nextInt(66 - 0) + 66;
        System.out.println(GenPass[Character]);
        GeneratedPass = GeneratedPass + GenPass[Character];
        i++;
    }
    return  GeneratedPass;
}
public void SendToDB(View v){
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch(item.getItemId()){
        case R.id.menuLogout:
            SharedPrefManager.getInstance(this).logout();
            finish();
            startActivity(new Intent(this, LoginActivity.class));
            break;
    }
    return true;
}
}

Answer 1

做

int Character = r.nextInt（66）;

而不是

int Character = r.nextInt（66 - 0）+ 66;

as＆＃34; r.nextInt（66-0）+ 66＆＃34;可以生成0到66之间的任何随机数，然后添加到该数字66，因此该字符的值大于66，这在数组中是不可访问的（长度为66），因此异常arrayIndexOutOfBoundsException。

或者为了使代码更健壮，而不是硬编码66，请使用：

    while (i < 13){
        Random r = new Random();
        int Character = r.nextInt(GenPass.length);
        System.out.println(GenPass[Character]);
        GeneratedPass = GeneratedPass + GenPass[Character];
        i++;
    }
    return  GeneratedPass;
}

Answer 2

String Generated_pass(){
    char[] GenPass = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
                      'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
                      'u', 'v', 'w', 'x', 'y', 'z', '1', '2', '3', '4',
                      '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E',
                      'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
                      'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y',
                      'Z', '@', '!', '?', '&', '%', '~'};
    int i = 1;
    String GeneratedPass = "";
    int min = 0;
    int max = 54;
    while (i < 13){
        Random r = new Random();
        int Character =r.nextInt(max - min + i) + min;
        System.out.println(GenPass[Character]);
        GeneratedPass = GeneratedPass + GenPass[Character];
        i++;
    }
    return  GeneratedPass;
}

试试此功能

从数组Android创建一个java字符串随机函数

2 个答案: