嗨，我想弄清楚如何将一个字符串从一个类传递到另一个类

问题描述

对不起所有代码。我试图传递的字符串是内容。

如果您需要更多信息请告诉我













这是我的主要班级 -

Sorry for all the code. The string I am trying to pass is contents.
Let me know if you need anymore info






here is my main class-

package com.app.david.booktracker;

import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.ClipData;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.MenuItem;
import android.view.View;
import android.view.Menu;
import android.widget.Toast;
import android.support.v7.widget.Toolbar;

public class MainActivity extends AppCompatActivity {

    static final String ACTION_SCAN = "com.google.zxing.client.android.SCAN";


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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    public void initToolBar() {

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        toolbar.setTitle("Book Tracker");
        setSupportActionBar(toolbar);


    }

    public void newBook(View view) {
        Intent intent = new Intent(this, NewBook.class);
        startActivity(intent);
    }

    public void showListBook(View view) {
        Intent intent = new Intent(this, ShowAllBooks.class);
        startActivity(intent);
    }


    public void scanBar(View v) {
        try {
            Intent intent = new Intent(ACTION_SCAN);
            intent.putExtra("SCAN_MODE", "PRODUCT_MODE");
            startActivityForResult(intent, 0);
        } catch (ActivityNotFoundException e) {
            showDialog(MainActivity.this, "No Scanner Found",
                    "Download a scanner code activity?", "Yes", "No").show();
        }
    }


    private static AlertDialog showDialog(final AppCompatActivity act,
                                          CharSequence title, CharSequence message, CharSequence buttonYes,
                                          CharSequence buttonNo) {

        AlertDialog.Builder dowloadDialog = new AlertDialog.Builder(act);
        dowloadDialog
                .setTitle(title)
                .setMessage(message)
                .setPositiveButton(buttonYes,
                        new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog,
                                                int which) {
                                Uri uri = Uri.parse("market://search?q=pname:"
                                        + "com.google.zxing.client.android");

                                Intent intent = new Intent(Intent.ACTION_VIEW,
                                        uri);
                                try {
                                    act.startActivity(intent);
                                } catch (ActivityNotFoundException e) {
                                }

                            }
                        })
                .setNegativeButton(buttonNo,
                        new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog,
                                                int which) {
                            }
                        });

        return dowloadDialog.show();
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
        if(requestCode == 0) {
            if(resultCode == RESULT_OK) {
                String contents = intent.getStringExtra("SCAN_RESULT");
                String format = intent.getStringExtra("SCAN_RESULT_FORMAT");
                Toast.makeText(this,
                        "Content:" + contents + " Format:" + format,
                        Toast.LENGTH_LONG).show();
            }
        }
    }





    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

这里是我试图将它传递给的类 -

Here is the class i am trying to pass it to -

package com.app.david.booktracker;

import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.os.Bundle;
import android.widget.Toast;
import android.support.v7.widget.Toolbar;


public class NewBook extends AppCompatActivity {

    private final static String TAG= "group4.NewBook";

    private EditText ean;

    @Override

    protected  void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.new_book);
        //initToolBar();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }


    public void initToolBar(){
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        toolbar.setTitle("Book Tracker");

        setSupportActionBar(toolbar);

        toolbar.setNavigationIcon(R.drawable.ic_toolbar_arrow);
        toolbar.setNavigationOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Intent intent = new Intent(v.getContext(), MainActivity.class);
                        startActivity(intent);
                    }
                }
        );
    }



    public void newBook(View view)
    {
        //Get the
        Intent intent=new Intent(this, MainActivity.class);
        EditText editTextBTitle=(EditText) findViewById(R.id.editTextFirstName);
        EditText editTextBAuthor=(EditText) findViewById(R.id.editTextSurname);

        String booktitle=editTextBTitle.getText().toString();
        String bookauthor=editTextBAuthor.getText().toString();

        String contents = intent.getStringExtra("SCAN_RESULT");
        DataHolder.bookadded(booktitle, bookauthor, contents);
        Log.d(TAG, " Added: " + booktitle + "  " + bookauthor + " " + contents);

        Toast.makeText(this, "Book Added! ", Toast.LENGTH_LONG).show();
        startActivity(intent);
    }


}

我的尝试：



我是java新手所以我可能犯了愚蠢的错误。我尝试过不同的方法来传递字符串而没有运气。如果我能够将字符串显示在一个很棒的edittextbox中。

What I have tried:

I am new to java so I am probably making silly mistakes. I have tried making different methods to pass the string with no luck. If I was able to get the string to appear in an edittextbox that would be great.

推荐答案

String contents = intent.getStringExtra("SCAN_RESULT");

BuT我看不到相应的 putExtra 将数据放入其中的调用。我假设你应该在main中做什么，然后NewBook活动可以使用 getStringExtra 来读取值。请参阅 []。

BuT I cannot see the corresponding putExtra call that puts the data in there. I assume that is what you should be doing in main and then the NewBook activity can use getStringExtra to read the value. See Intent | Android Developers[^].

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