我已经开始了另一个从另一个类中获取两个字符串的类，到目前为止我只设置了一个，但我只是测试了它，但是当我填写我的两个编辑文本并点击提交时它会崩溃。
头等舱（发射器级别）
package com.gta5news.bananaphone;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.R.string;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class LogIn extends Activity implements OnClickListener {
Button send;
EditText user;
EditText pass;
CheckBox staySignedIn;
FileOutputStream Fos;
String FILENAME = "userandpass";
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
send = (Button) findViewById(R.id.bLogIn);
user = (EditText) findViewById(R.id.eTuser);
pass = (EditText) findViewById(R.id.eTpassword);
staySignedIn = (CheckBox) findViewById(R.id.Cbstay);
send.setOnClickListener(this);
try {
Fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
Fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (staySignedIn.isChecked()) {
String a = user.getText().toString();
String b = pass.getText().toString();
File f = new File(FILENAME);
try {
Fos = new FileOutputStream(f);
//Write some Data
Fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.bLogIn:
if (pass.length() == 0)
Toast.makeText(this,
"Try to type in your username and password again!",
Toast.LENGTH_LONG).show();
else if (user.length() == 0)
Toast.makeText(this,
"Try to type in your username and password again!",
Toast.LENGTH_LONG).show();
else {
String u = user.getText().toString();
String p = pass.getText().toString();
Bundle send = new Bundle();
send.putString("key", u);
send.putString("key", p);
Intent a = new Intent(LogIn.this, logincheck.class);
startActivity(a);
Toast.makeText(this, "Were signing you in!", Toast.LENGTH_LONG)
.show();
break;
}
}
}
}
第二课：
package com.gta5news.bananaphone;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class logincheck extends Activity {
String GotBread;
TextView user;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.logincheck);
user = (TextView) findViewById(R.layout.logincheck);
SetUp();
}
public void SetUp() {
// TODO Auto-generated method stub
Bundle GotData = getIntent().getExtras();
GotBread = GotData.getString("key");
user.setText(GotBread); {
}
}
}
logcat的：
01-19 08:53:56.641: E/AndroidRuntime(3319): ... 11 more
01-19 08:56:28.561: E/AndroidRuntime(3384): FATAL EXCEPTION: main
01-19 08:56:28.561: E/AndroidRuntime(3384): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gta5news.bananaphone/com.gta5news.bananaphone.logincheck}: java.lang.NullPointerException
01-19 08:56:28.561: E/AndroidRuntime(3384): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
01-19 08:56:28.561: E/AndroidRuntime(3384): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
01-19 08:56:28.561: E/AndroidRuntime(3384): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
01-19 08:56:28.561: E/AndroidRuntime(3384): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
01-19 08:56:28.561: E/AndroidRuntime(3384): at android.os.Handler.dispatchMessage(Handler.java:99)
01-19 08:56:28.561: E/AndroidRuntime(3384): at android.os.Looper.loop(Looper.java:123)
01-19 08:56:28.561: E/AndroidRuntime(3384): at android.app.ActivityThread.main(ActivityThread.java:4627)
01-19 08:56:28.561: E/AndroidRuntime(3384): at java.lang.reflect.Method.invokeNative(Native Method)
01-19 08:56:28.561: E/AndroidRuntime(3384): at java.lang.reflect.Method.invoke(Method.java:521)
01-19 08:56:28.561: E/AndroidRuntime(3384): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-19 08:56:28.561: E/AndroidRuntime(3384): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-19 08:56:28.561: E/AndroidRuntime(3384): at dalvik.system.NativeStart.main(Native Method)
01-19 08:56:28.561: E/AndroidRuntime(3384): Caused by: java.lang.NullPointerException
01-19 08:56:28.561: E/AndroidRuntime(3384): at com.gta5news.bananaphone.logincheck.SetUp(logincheck.java:24)
01-19 08:56:28.561: E/AndroidRuntime(3384): at com.gta5news.bananaphone.logincheck.onCreate(logincheck.java:17)
01-19 08:56:28.561: E/AndroidRuntime(3384): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-19 08:56:28.561: E/AndroidRuntime(3384): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
01-19 08:56:28.561: E/AndroidRuntime(3384): ... 11 more
答案 0 :(得分：0)
在您的主要活动中，您正在创建Bundle并在其中插入内容，但您不会将其发送到意图。
您应该在开始第二个活动之前将信息放在Intent上。做这样的事情：
Intent a = new Intent(LogIn.this, logincheck.class);
a.putExtra("key", u);
a.putExtra("key", p);
startActivity(a);
答案 1 :(得分：0)
在Oncreate方法中获取捆绑
使用喜欢
Intent i = new Intent(Login.this,logincheck.class);
i.putExtra("key", user);
i.putExtra("key1", pass);
startActivity(i);
和
user = (TextView) findViewById(R.layout.logincheck);
而不是
user = (TextView) findViewById(R.id.logincheck);
所以用户是空的
答案 2 :(得分：0)
我会试着给你一个如何解决它的线索..这可能会更加失败，但这应该对你有用..
Intent i = new Intent(LogIn.this, logincheck.class);
i.putExtra("username", sUsername);
i.putExtra("password", SPassword);
要在新活动中获取已保存的数据，请尝试使用：
String newString;
if(extras == null) {
sUsernameInNewActivity = null;
sPasswordInNewActivity = null;
} else {
sUsernameInNewActivity = extras.getString("username");
sPasswordInNewActivity = extras.getString("password");
}
顺便说一句。在您的代码中有很多不好的做法.. :(我有麻烦阅读它很容易.. 例如：
你想加入这个代码或???
send.putString（“key”，u）; send.putString（“key”，p）;