Android 输入数据后返回数据列表_Android_Android Intent_Android Activity

Android 输入数据后返回数据列表

android

Android 输入数据后返回数据列表,android,android-intent,android-activity,Android,Android Intent,Android Activity,我有三项活动，主要活动，其他活动，第三项活动 public class OtherActivity extends Activity { EditText Name, Age, MPersonal, MBTI, Birthday, SNotes; Button second button, third button; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedI

我有三项活动，主要活动，其他活动，第三项活动

public class OtherActivity extends Activity {

EditText Name, Age, MPersonal, MBTI, Birthday, SNotes;
Button second button, third button;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.other_activity);
    Intent myIntent = getIntent();
    secondbutton = (Button)findViewById(R.id.secondbutton);
    thirdbutton = (Button)findViewById(R.id.button3);
    Name = (EditText) findViewById(R.id.editText);
    Age = (EditText) findViewById(R.id.editText2);
    MPersonal = (EditText) findViewById(R.id.editText3);
    MBTI = (EditText) findViewById(R.id.editText4);
    Birthday = (EditText) findViewById(R.id.editText5);
    SNotes = (EditText) findViewById(R.id.editText6);

}
public void onClick2(View view) {
    Intent backIntent = new Intent(OtherActivity.this, MainActivity.class);
    OtherActivity.this.startActivity(backIntent);
}
public void onClick3(View view) {
    Intent bintent = new Intent(this, ThirdActivity.class);
    Bundle bbundle = new Bundle();
    bbundle.putString("name", Name.getText().toString());
    bbundle.putString("age", Age.getText().toString());
    bbundle.putString("mper", MPersonal.getText().toString());
    bbundle.putString("mbti", MBTI.getText().toString());
    bbundle.putString("birthday", Birthday.getText().toString());
    bbundle.putString("special", SNotes.getText().toString());
    bintent.putExtras(bbundle);
    startActivity(bintent);

}
}

MainActivity作为主菜单，通过按钮指向其他活动：

public void onClick(View v) {
        Intent myIntent = new Intent(MainActivity.this, OtherActivity.class);
        MainActivity.this.startActivity(myIntent);
    }

然后在OtherActivity中包含需要输入下一个活动（第三个活动）的数据表单列表

public class OtherActivity extends Activity {

EditText Name, Age, MPersonal, MBTI, Birthday, SNotes;
Button second button, third button;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.other_activity);
    Intent myIntent = getIntent();
    secondbutton = (Button)findViewById(R.id.secondbutton);
    thirdbutton = (Button)findViewById(R.id.button3);
    Name = (EditText) findViewById(R.id.editText);
    Age = (EditText) findViewById(R.id.editText2);
    MPersonal = (EditText) findViewById(R.id.editText3);
    MBTI = (EditText) findViewById(R.id.editText4);
    Birthday = (EditText) findViewById(R.id.editText5);
    SNotes = (EditText) findViewById(R.id.editText6);

}
public void onClick2(View view) {
    Intent backIntent = new Intent(OtherActivity.this, MainActivity.class);
    OtherActivity.this.startActivity(backIntent);
}
public void onClick3(View view) {
    Intent bintent = new Intent(this, ThirdActivity.class);
    Bundle bbundle = new Bundle();
    bbundle.putString("name", Name.getText().toString());
    bbundle.putString("age", Age.getText().toString());
    bbundle.putString("mper", MPersonal.getText().toString());
    bbundle.putString("mbti", MBTI.getText().toString());
    bbundle.putString("birthday", Birthday.getText().toString());
    bbundle.putString("special", SNotes.getText().toString());
    bintent.putExtras(bbundle);
    startActivity(bintent);

}
}

它工作得很好，它直接将意图发送到第三个活动，即：

public class ThirdActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.data_activity);
    TextView nameView = (TextView) findViewById(R.id.nametext);
    nameView.setText(getIntent().getExtras().getString("name"));
    TextView ageView = (TextView) findViewById(R.id.agetext);
    ageView.setText(getIntent().getExtras().getString("age"));
    TextView mperView = (TextView) findViewById(R.id.mpersonalitytext);
    mperView.setText(getIntent().getExtras().getString("mper"));
    TextView mbtiView = (TextView) findViewById(R.id.mbtitext);
    mbtiView.setText(getIntent().getExtras().getString("mbti"));
    TextView birthdayView = (TextView) findViewById(R.id.birthdaytext);
    birthdayView.setText(getIntent().getExtras().getString("birthday"));
    TextView specialView = (TextView) findViewById(R.id.specialtext);
    specialView.setText(getIntent().getExtras().getString("special"));
}

ThirdActivity内部还包含onClick函数和重定向到主菜单：

    public void Clicky (View vclicky) {
    Intent intentclick = new Intent(ThirdActivity.this, MainActivity.class);
    ThirdActivity.this.startActivity(intentclick);
}

它工作得很好。但当我试图返回到第三个活动时，它列出了输入的数据。尝试单击按钮时出错：

public void onClicky(View vclick) {
    Intent kuriki = new Intent(MainActivity.this, ThirdActivity.class);
    MainActivity.this.startActivity(kuriki);
}

错误消息显示：

E/AndroidRuntime:致命异常：主进程：com.example.user.myapplication，PID:3739 java.lang.RuntimeException:无法启动activity ComponentInfo{com.example.user.myapplication/com.example.user.myapplication.ThirdActivity}:java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“java.lang.String android.os.BaseBundle.getString（java.lang.String）” 在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2646）上位于android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2707）位于android.app.ActivityThread.-wrap12（ActivityThread.java）

底线是，当我尝试在OtherActivity中输入数据时，输入的数据以TextView的形式保存在ThirdActivity中。返回按钮将返回主菜单，主菜单为MainActivity。然后，当我试图通过点击按钮查看数据，直接到第三个活动。发生错误

你能帮我解释一下为什么我不能返回到输入的数据，同时我认为我不理解错误信息。提前感谢

很抱歉迟到了，但我已经搜索并尝试了很多次向您解释，并知道错误在哪里，最开始的错误是您在帖子中阅读/提供的日志，这些行对您没有用处，也无法帮助您了解这一行

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
                                                                                                      at com.blogspot.dictionary.coding.android.tempdeletemenow.ThirdActivity.onCreate(ThirdActivity.java:32)

它描述了错误，并表示代码中的第X行（我是32行）中有错误那是

nameView.setText(getIntent().getExtras().getString("name"));

    public void onClicky(View vclick) {
    Intent kuriki = new Intent(MainActivity.this, ThirdActivity.class);
    MainActivity.this.startActivity(kuriki);
}

首先

getIntent（）.getExtras（）.getString（“name”）

意味着您从启动此活动的Intent获取已保存的数据（Extras），该活动是

nameView.setText(getIntent().getExtras().getString("name"));

    public void onClicky(View vclick) {
    Intent kuriki = new Intent(MainActivity.this, ThirdActivity.class);
    MainActivity.this.startActivity(kuriki);
}

（在直接启动ViewData的情况下）没有额外内容（保存的数据（姓名、年龄…），So首先输入数据，然后查看的意图将起作用，而查看否（空）数据时，意图将崩溃

解决方案是：-

1。在ThirdadActivit中：

public class MainActivity extends Activity {

static Intent bintent;

@Override
protected void onCreate(Bundle savedInstanceState) {

添加检查意图是否有数据（附加）的If语句
还检查其自身的意图是否不为空
将
```
getIntent（）
```
替换为
```
bintent
```
Intent
最后在应用程序上共享
```
bintent
```
意图，以便通过
```
static
```

像这样

import static com.blogspot.dictionary.coding.android.tempdeletemenow.MainActivity.bintent;


public class ThirdActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.data_activity);

    if (bintent != null) {
        if (bintent.hasExtra("name")) {
            TextView nameView = (TextView) findViewById(R.id.nametext);
            TextView ageView = (TextView) findViewById(R.id.agetext);
            TextView mperView = (TextView) findViewById(R.id.mpersonalitytext);
            TextView mbtiView = (TextView) findViewById(R.id.mbtitext);
            TextView birthdayView = (TextView) findViewById(R.id.birthdaytext);
            TextView specialView = (TextView) findViewById(R.id.specialtext);

            nameView.setText(bintent.getExtras().getString("name"));
            ageView.setText(bintent.getExtras().getString("age"));
            mperView.setText(bintent.getExtras().getString("mper"));
            mbtiView.setText(bintent.getExtras().getString("mbti"));
            birthdayView.setText(bintent.getExtras().getString("birthday"));
            specialView.setText(bintent.getExtras().getString("special"));
        }
    }
}

2。在主活动中

public class MainActivity extends Activity {

static Intent bintent;

@Override
protected void onCreate(Bundle savedInstanceState) {

3。最后，在其他活动中

import static com.blogspot.dictionary.coding.android.tempdeletemenow.MainActivity.bintent;

在

bintent=newintent之前删除Intent
（this，ThirdActivity.class）
我无法理解错误，或者我认为它可能遗漏了主线，那么，你能给我一个应用程序的源代码吗？我可以在我的AndroidStudio上运行它来尝试解决它？我如何给应用程序的源代码？我应该给xml和java文件吗？是的，好吧，这对你来说比较容易我很抱歉迟到了，但我一直在搜索它，以便向你解释。非常感谢你回答我的问题。对不起，我在这件事上不耐烦了。因为我必须完成最后的任务。我一定要把你的名字写在我的最终报告中。非常感谢您（欢迎，没关系，很高兴帮助您：）