Question

我正在尝试制作一个应用程序来列出我所在地区的学校，并在数据库中创建了一个包含这些学校的表格。我制作了一个带有可点击项目的列表视图，列出了学校的名称，当我点击该项目移动到另一个活动并发送点击的学校名称以列出有关学校的更多信息时，该应用程序停止工作。以下是包含此列表视图的活动之一：

package com.example.welcome.madrasti;

import android.content.Intent;
import android.database.Cursor;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;

public class ListOfSchoolsPublic extends AppCompatActivity {

        Intent redirect;
        Intent item;
        ListView list;
        ArrayList<String>  _sa;
        DBAdapter db;

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

            openDB();

            list= (ListView) findViewById(R.id.usersList);

            redirect = getIntent();

            Cursor cursor = db.getAllRows();

            _sa= new  ArrayList<String>();

            //cursor.moveToFirst();

            Log.d("CURSORCOUNT","Number of rows in the Cursor is = " + String.valueOf(cursor.getCount()));




            while(cursor.moveToNext()) {

                if(cursor.getString(DBAdapter.COL_SChOOL_TYPE_TABLE_2).equals("حكومية"))
                _sa.add(cursor.getString(DBAdapter.COL_SCHOOLNAME_TABLE_2));

            }

            cursor.close();


            @SuppressWarnings("rawtypes")
            ArrayAdapter adapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1,_sa);

            list.setAdapter(new TempLyaout(ListOfSchoolsPublic.this,_sa));


           list.setOnItemClickListener(new AdapterView.OnItemClickListener()
            {
                @Override
                public void onItemClick(AdapterView<?> arg0, View arg1,int position, long arg3)
                {

                    String selectedItem = (String) arg0.getItemAtPosition(position);

                    itemInfo(selectedItem);
                }
            });



    }

    ///////////////////////////////////////////////////////////////

    public void itemInfo(String selectedItem){

           item = new Intent(getApplicationContext(), NewSchool.class);

           item.putExtra("schoolName",selectedItem);

           startActivity(item);

    }

    ///////////////////////////////////////////////////////////////
    @Override
    protected void onDestroy() {
        super.onDestroy();
        closeDB();

    }// end onDestroy method



    ///////////////////////////////////////////////////////////////

    private void openDB() {
        db = new DBAdapter(ListOfSchoolsPublic.this);
        db.open();
    } // end openDB method

    //////////////////////////////////////////////////////////////

    private void closeDB() {
        db.close();
    } // end closeDB method

}

以下是每个列表项应移至的活动：

package com.example.welcome.madrasti;

import android.content.Intent;
import android.database.Cursor;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class NewSchool extends AppCompatActivity {

    Intent intent;

    Intent nextPage;

    Button next;

    DBAdapter db;

    TextView t1;

    TextView t2;

    TextView t3;

    TextView t4;

    TextView t5;



    String name;


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

        t1=(TextView)findViewById(R.id.textView9) ;
        t2=(TextView)findViewById(R.id.textView11) ;
        t3=(TextView)findViewById(R.id.textView12) ;
        t4=(TextView)findViewById(R.id.textView17) ;
        t5=(TextView)findViewById(R.id.textView18) ;


        next = (Button) findViewById(R.id.button);
        intent = getIntent();

        name = intent.getStringExtra("schoolName");

        next.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                goNext();
            }
        });

        Cursor cursor = db.getAllRows();

        while(cursor.moveToNext()) {

            if(cursor.getString(DBAdapter.COL_SCHOOLNAME_TABLE_2).equals(name)){

                t1.setText(DBAdapter.COL_SCHOOLNAME_TABLE_2);
                t2.setText(DBAdapter.COL_FOUNDATION_DATE_TABLE_2);
                t3.setText(DBAdapter.COL_BUY_BOOKS_TABLE_2);
                t4.setText(DBAdapter.COL_HEALTH_TABLE_2);
                t5.setText(DBAdapter.COL_LOCATION_TABLE_2);

            }


        }

        cursor.close();


    }


    public void goNext(){

        nextPage = new Intent(getApplicationContext(),NewShoolAct2.class);
        nextPage.putExtra("schoolName",name);
        startActivity(nextPage);

    }

    ///////////////////////////////////////////////////////////////
    @Override
    protected void onDestroy() {
        super.onDestroy();
        closeDB();

    }// end onDestroy method



    ///////////////////////////////////////////////////////////////

    private void openDB() {
        db = new DBAdapter(NewSchool.this);
        db.open();
    } // end openDB method

    //////////////////////////////////////////////////////////////

    private void closeDB() {
        db.close();
    } // end closeDB method


}

以下是上一个活动的XML：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/login_background"
    tools:context="com.example.welcome.madrasti.NewSchool">

    <AbsoluteLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:layout_editor_absoluteX="16dp"
        tools:layout_editor_absoluteY="0dp">


        <TextView
            android:id="@+id/textView"
            android:layout_width="80dp"
            android:layout_height="30dp"
            android:layout_x="244dp"
            android:layout_y="54dp"
            android:text="إسم المدرسة:"
            android:textAlignment="center"
            android:textStyle="bold"
            tools:layout_editor_absoluteX="dp"
            tools:layout_editor_absoluteY="10dp" />

        <TextView
            android:id="@+id/textView3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="240dp"
            android:layout_y="127dp"
            android:text="تاريخ التأسيس:"
            android:textAlignment="center"
            android:textStyle="bold"
            tools:layout_editor_absoluteX="297dp"
            tools:layout_editor_absoluteY="144dp" />

        <TextView
            android:id="@+id/textView4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="231dp"
            android:layout_y="185dp"
            android:text="كيفية شراء الكتب:"
            android:textAlignment="center"
            android:textStyle="bold"
            tools:layout_editor_absoluteX="284dp"
            tools:layout_editor_absoluteY="210dp" />

        <TextView
            android:id="@+id/textView5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="215dp"
            android:layout_y="265dp"
            android:text="وضع المرافق الصحية:"
            android:textAlignment="center"
            android:textStyle="bold"
            tools:layout_editor_absoluteX="265dp"
            tools:layout_editor_absoluteY="288dp" />

        <TextView
            android:id="@+id/textView6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="244dp"
            android:layout_y="340dp"
            android:text="موقع المدرسة:"
            android:textAlignment="center"
            android:textStyle="bold"
            tools:layout_editor_absoluteX="300dp"
            tools:layout_editor_absoluteY="368dp" />

        <Button
            android:id="@+id/button"
            android:layout_width="98dp"
            android:layout_height="34dp"
            android:layout_x="133dp"
            android:layout_y="434dp"
            android:background="@drawable/button"
            android:text="التالي"
            android:textAlignment="center"
            android:textColor="#ffff"
            android:textStyle="bold"
            tools:layout_editor_absoluteX="45dp"
            tools:layout_editor_absoluteY="426dp" />

        <TextView
            android:id="@+id/textView9"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="11dp"
            android:layout_y="77dp"
            android:text="TextView"
            tools:layout_editor_absoluteX="18dp"
            tools:layout_editor_absoluteY="59dp" />

        <TextView
            android:id="@+id/textView11"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="12dp"
            android:layout_y="148dp"
            android:text="TextView"
            tools:layout_editor_absoluteX="12dp"
            tools:layout_editor_absoluteY="150dp" />

        <TextView
            android:id="@+id/textView12"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="32345dp"
            android:layout_y="32418dp"
            android:text="TextView"
            tools:layout_editor_absoluteX="16dp"
            tools:layout_editor_absoluteY="235dp" />

        <TextView
            android:id="@+id/textView17"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="15dp"
            android:layout_y="299dp"
            android:text="TextView"
            tools:layout_editor_absoluteX="21dp"
            tools:layout_editor_absoluteY="37dp" />

        <TextView
            android:id="@+id/textView18"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="16dp"
            android:layout_y="372dp"
            android:text="TextView"
            tools:layout_editor_absoluteX="17dp"
            tools:layout_editor_absoluteY="381dp" />

        <TextView
            android:id="@+id/textView20"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_x="16dp"
            android:layout_y="219dp"
            android:text="TextView"
            tools:layout_editor_absoluteX="10dp"
            tools:layout_editor_absoluteY="215dp" />
    </AbsoluteLayout>

</android.support.constraint.ConstraintLayout>

以下是应用崩溃时的日志cat：

04-13 17:57:49.245 5828-5828/? E/libprocessgroup: failed to make and chown /acct/uid_10059: Read-only file system
04-13 17:57:49.245 5828-5828/? W/Zygote: createProcessGroup failed, kernel missing CONFIG_CGROUP_CPUACCT?
04-13 17:57:49.245 5828-5828/? I/art: Late-enabling -Xcheck:jni
04-13 17:57:49.435 5828-5838/? I/art: Debugger is no longer active
04-13 17:57:49.492 5828-5828/? I/InstantRun: starting instant run server: is main process
04-13 17:57:49.602 5828-5843/? W/art: Suspending all threads took: 11.737ms
04-13 17:57:49.605 5828-5843/? I/art: Background sticky concurrent mark sweep GC freed 2038(168KB) AllocSpace objects, 0(0B) LOS objects, 25% free, 832KB/1117KB, paused 13.068ms total 21.305ms
04-13 17:57:49.630 5828-5828/? W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
04-13 17:57:49.779 5828-5847/? D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
04-13 17:57:49.784 5828-5828/? D/Atlas: Validating map...
04-13 17:57:49.810 5828-5847/? D/libEGL: loaded /system/lib/egl/libEGL_emulation.so
    loaded /system/lib/egl/libGLESv1_CM_emulation.so
04-13 17:57:49.820 5828-5847/? D/libEGL: loaded /system/lib/egl/libGLESv2_emulation.so
04-13 17:57:49.848 5828-5847/? I/OpenGLRenderer: Initialized EGL, version 1.4
04-13 17:57:49.878 5828-5847/? D/OpenGLRenderer: Enabling debug mode 0
04-13 17:57:49.896 5828-5847/? W/EGL_emulation: eglSurfaceAttrib not implemented
04-13 17:57:49.896 5828-5847/? W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xe2c15340, error=EGL_SUCCESS

请问有什么问题？怎么解决？

Answer 1

您可以将字符串存储到其他类中：

存储字符串：

String selectedItem = (String) arg0.getItemAtPosition(position);

Share.love=selectedItem ;

获取字符串：

在你的下一个活动中

Textview textview=(Textview)findviewbyid(R.id.yourname);
textview.setText(Share.love);

上课

public class Share {

public static String love = "";

}

Answer 2

使用意图并首先阅读基本的android。有许多选项可供选择。

Answer 3

尝试以下示例（它使用putExtra（）将字符串传递给另一个活动）：

Demo15.class：------------

public class Demo15 extends AppCompatActivity {

private Button b;
private EditText edt;
private final String EXTRA_TEXT_ = "extra_text_";

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.demo17);

    edt = (EditText) findViewById(R.id.edt);

    b = (Button) findViewById(R.id.b);
    b.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent i = new Intent(Demo15.this, Demo16.class);
            if (!edt.getText().toString().isEmpty()) {
                i.putExtra(EXTRA_TEXT_, edt.getText().toString());
            }
            startActivity(i);
        }
    });
}
}

Demo16.class：-------

public class Demo16 extends AppCompatActivity {

private TextView tv;
private final String EXTRA_TEXT_ = "extra_text_";

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.demo18);

    tv = (TextView) findViewById(R.id.tv);

    if (getIntent() != null) {
        if (getIntent().getStringExtra(EXTRA_TEXT_) != null) {
            tv.setText(getIntent().getStringExtra(EXTRA_TEXT_));
        }
    }
}
}

demo17.xml：-------

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="Enter text to pass"
    android:id="@+id/edt"/>

<Button
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Start the other activity"
    android:textAllCaps="false"
    android:layout_marginTop="50dp"
    android:id="@+id/b"/>

</LinearLayout>

demo18.xml：---------

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
android:layout_height="match_parent">

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="####"
    android:id="@+id/tv"/>

</android.support.constraint.ConstraintLayout>

Answer 4

使用带有意图的bundle作为android标准。例如：

Intent intent=new Intent(CurrentActivity.this,NewActivity.class);
intent.putExtra("schoolname","Name of school");
startActivity

如何将字符串从一个活动发送到另一个活动

4 个答案: