Question

对于学校项目，我正在创建一个简单的应用程序。但是，我遇到了一个问题来完成应用程序。

我一直试图在主要布局上制作两个按钮。按钮应该打开第二个布局，一个名为barcode_scanner.xml，另一个名为vragen.xml

但是，只有第一个按钮才能打开扫描仪。第二个按钮没有任何作用。

这是我目前来自MainActivity.java的代码

package com.kvprasad.zbarbarcodescanner;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    private Button scannerButton;

@Override
        //Barcodescanner knop
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            Button next = (Button) findViewById(R.id.scannerButton);
            next.setOnClickListener(new View.OnClickListener() {
                public void onClick(View view) {
                    Intent myIntent = new Intent(view.getContext(), BarcodeScanner.class);
                    startActivityForResult(myIntent, 0);
                }
            });
        }




    @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;
    }

    @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);
    }








public class bovenbouw extends MainActivity{

    @Override
                public void onCreate(Bundle savedInstanceState) {
                    super.onCreate(savedInstanceState);
                    setContentView(R.layout.activity_main);
                    Button next = (Button) findViewById(R.id.bovenbutton);
                    next.setOnClickListener(new View.OnClickListener() {
                        public void onClick(View view) {
                            Intent myIntent = new Intent(view.getContext(), Vragen.class);
                            startActivityForResult(myIntent, 0);}});}}}

我没有在代码中看到任何问题。我可能做错了什么？谢谢。

Answer 1

不要为同一活动制作多个onCreate方法。使用相同的onCreate方法处理所有按钮点击。你能做的是：

package com.kvprasad.zbarbarcodescanner;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

private Button scannerButton;

@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;
}

@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);
}

@Override
//Barcodescanner knop
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Button next1 = (Button) findViewById(R.id.scannerButton);
    next.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            Intent myIntent = new Intent(view.getContext(), BarcodeScanner.class);
            startActivityForResult(myIntent, 0);
        }
    });

    Button next2 = (Button) findViewById(R.id.bovenbutton);
    next.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            Intent myIntent = new Intent(view.getContext(), Vragen.class);
            startActivityForResult(myIntent, 0);}

        });
    }
}

Answer 2

两个按钮不需要2个onCreate()方法。由于它们都采用相同的布局，因此您只能在一种方法中为它们设置onClickListener。

public class MainActivity extends AppCompatActivity {

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

        Button next = (Button) findViewById(R.id.scannerButton);
        next.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                Intent myIntent = new Intent(this, BarcodeScanner.class);
                startActivityForResult(myIntent, 0);
            }
        });

        Button next1 = (Button) findViewById(R.id.bovenbutton);
        next.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                Intent myIntent = new Intent(this, Vragen.class);
                startActivityForResult(myIntent, 1); 
                //Make sure the second parameter is not 0, so that you can differentiate between them in onActivityReult method.
            }
        });
    }
}

Answer 3

按下 bovenbutton 后，您不必为 vragen.class 创建另一个类。除了 scanner_batton

之外，只需在主要类 oncreate 方法中为 bovenbutton 创建另一个按钮

@Override
//Barcodescanner knop
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Button next = (Button) findViewById(R.id.scannerButton);
    Button vragen = (Button) findViewById(R.id.bovenbutton);//button for vragen
    next.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            Intent myIntent = new Intent(view.getContext(), BarcodeScanner.class);
            startActivityForResult(myIntent, 0);
        }
    });
   //here goes the onclicklistener for vragen button
   vragen.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            Intent myIntent = new Intent(view.getContext(), Vragen.class);
            startActivityForResult(myIntent, 0);
        }
    });
}

Answer 4

您不应该在单个.java文件中注册两个活动。您必须创建单独的活动。

Answer 5

package com.example.photosapp

import android.support.v7.app.AppCompatActivity
import android.os.Bundle

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }
}

Android Studio MainActivity.java中的多个onCreate方法

5 个答案: