如何解决java.lang问题。”；“非法国家例外”&引用；StringIndexOutOfBound“&引用；InvocationTargetException“；

有人能帮我写这个应用程序，但它不工作，我没有找到解决方案

第一个错误：由java.lang.IllegalStateException引起：无法执行活动的方法

第二个错误：由java.lang.StringIndexOutOfBoundException引起

第三个错误：由java.lang.reflect.InvocationTargetException引起

package com.enkripsms;

import com.dbutil.dbhelper;
import android.app.Activity;
import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class tulisPesan extends Activity {
/**
 * @see android.app.Activity#onCreate(Bundle)
 */
EditText pesan;
EditText kunci;
private SQLiteDatabase db = null;
private dbhelper data = null;

@Override

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // TODO Put your code here
    setContentView(R.layout.tulispesan);
    data = new dbhelper(this);
    db = data.getWritableDatabase();
    data.createTable(db);       
}

public void sandikan ( View s ) {
    kunci = (EditText)findViewById(R.id.kunci);
    pesan = (EditText)findViewById(R.id.pesan);
    String kuncinya = kunci.getText().toString();
    String plain = pesan.getText().toString();
    String chiper = "";

    if (kuncinya.isEmpty()) { //(kunci == null)
        Toast.makeText(this, "Maaf, kunci harus diisi", Toast.LENGTH_LONG).show();
    }else{
        String acak = "";
        double acakN;
        for (int a = 0; a<kuncinya.length(); a++) {
            acakN = Math.random() * 25 + 65;
            acak = acak + (char) acakN;
        }
        kunci.setText(acak); 
    }

    if (kuncinya.length() != plain.length()) {
        for (int a = 0; a<plain.length(); a++) {
            String tambahk = "";
            tambahk = tambahk + kuncinya.substring(0, 1);
            kuncinya = tambahk;
        }
        kunci.setText(kuncinya);
    }

    for (int a = 0; a<plain.length(); a++) {
        String plainBin = "0" + Integer.toBinaryString((int)plain.charAt(a));

        if (plainBin.length() < 8) 
            plainBin = "0" + plainBin;

        String keyBin = "0" + Integer.toBinaryString((int)kuncinya.charAt(a));

        for (int b = 0; b<8; b++) {
            chiper = chiper + Integer.toString((Integer.parseInt(plainBin.substring(b, b+1))) ^ Integer.parseInt(keyBin.substring(b, b+1)));
        }       
    }
    Intent hasilPesan = new Intent();
    hasilPesan.setClass(this, hasilPesan.class);
    hasilPesan.putExtra("chiper", chiper);
    startActivity(hasilPesan);
}

public void inputData () {

}

public void kembali ( View k) {
    Intent kembali = new Intent();
    kembali.setClass(this, MainActivity.class);
    startActivity(kembali);
}


}

有人请帮帮我，谢谢你。

在你的for循环中：

chiper = chiper + Integer.toString((Integer.parseInt(plainBin.substring(b, b+1))) ^ Integer.parseInt(keyBin.substring(b, b+1)));

超过字符串的长度

看这一行，检查你想循环8次

for (int b = 0; b<8; b++) {

for（int b=0；b
for (int b = 0; b<8; b++) {