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问题是从五个复选框中选择一个选项，并在另一个页面中显示所选选项的结果。

我在应用中有 2 个活动。

所有的编码都是在java文件上完成的，没有在xml文件中添加任何代码。

MainActivity.java

import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.*;
import android.view.View.*;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.LinearLayout;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Q3
                LinearLayout ll3 = new LinearLayout(this);
                ll3.setOrientation(LinearLayout.VERTICAL);


                final List <CheckBox> cbs = new ArrayList<CheckBox>();

                for(int i = 0; i < 5; i++){
                    CheckBox cb = new CheckBox(this);
                    cb.setText("Apple" + (i + 1));
                    ll3.addView(cbs.get(i));
                }



                Button button3 = new Button(this);
                button3.setText("Select");

                button3.setOnClickListener(new OnClickListener(){

                    public void onClick(View v) {
                        StringBuffer str = new StringBuffer();

                        for(int i = 0; i < cbs.size(); i++){
                            if(cbs.get(i).isChecked()){
                                str.append(cbs.get(i).getText().toString() + "; ");
                            }
                        }

                        Intent i = new Intent(MainActivity.this,MainActivity2.class);
                        i.putExtra("checked", str.toString());
                        startActivity(i);
                    }
                });

                ll3.addView(button3);
                setContentView(ll3);
    }



}

而对于另一个活动文件名 MainActivity2.java

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity2 extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_activity2);

        //Q3
                TextView tv = new TextView(this);
                tv.setText("You have selected:");
                TextView tv1 = new TextView(this);
                tv1.setText(this.getIntent().getStringExtra("checked"));

                LinearLayout ll3 = new LinearLayout(this);
                ll3.setOrientation(LinearLayout.VERTICAL);
                ll3.addView(tv);
                ll3.addView(tv1);
                setContentView(ll3);
    }


}

当我运行应用程序时，它显示无法运行的错误消息状态。任何问题？

日志文件

02-20 08:09:07.274: D/AndroidRuntime(376): Shutting down VM
02-20 08:09:07.274: W/dalvikvm(376): threadid=1: thread exiting with uncaught exception (group=0x40015560)
02-20 08:09:07.303: E/AndroidRuntime(376): FATAL EXCEPTION: main
02-20 08:09:07.303: E/AndroidRuntime(376): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.practical033/com.practical033.MainActivity}: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
02-20 08:09:07.303: E/AndroidRuntime(376):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
02-20 08:09:07.303: E/AndroidRuntime(376):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
02-20 08:09:07.303: E/AndroidRuntime(376):  at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-20 08:09:07.303: E/AndroidRuntime(376):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
02-20 08:09:07.303: E/AndroidRuntime(376):  at android.os.Handler.dispatchMessage(Handler.java:99)
02-20 08:09:07.303: E/AndroidRuntime(376):  at android.os.Looper.loop(Looper.java:123)
02-20 08:09:07.303: E/AndroidRuntime(376):  at android.app.ActivityThread.main(ActivityThread.java:3683)
02-20 08:09:07.303: E/AndroidRuntime(376):  at java.lang.reflect.Method.invokeNative(Native Method)
02-20 08:09:07.303: E/AndroidRuntime(376):  at java.lang.reflect.Method.invoke(Method.java:507)
02-20 08:09:07.303: E/AndroidRuntime(376):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-20 08:09:07.303: E/AndroidRuntime(376):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-20 08:09:07.303: E/AndroidRuntime(376):  at dalvik.system.NativeStart.main(Native Method)
02-20 08:09:07.303: E/AndroidRuntime(376): Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
02-20 08:09:07.303: E/AndroidRuntime(376):  at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:257)
02-20 08:09:07.303: E/AndroidRuntime(376):  at java.util.ArrayList.get(ArrayList.java:311)
02-20 08:09:07.303: E/AndroidRuntime(376):  at com.practical033.MainActivity.onCreate(MainActivity.java:32)
02-20 08:09:07.303: E/AndroidRuntime(376):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-20 08:09:07.303: E/AndroidRuntime(376):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
02-20 08:09:07.303: E/AndroidRuntime(376):  ... 11 more
02-20 08:09:09.733: I/Process(376): Sending signal. PID: 376 SIG: 9
4

2 回答 2

1

您可以使用两种方法 - 使用静态变量并将复选框值赋予该变量并将其访问到另一个活动 - 使用意图从第一个活动传递数据传递值并在其他示例中接收额外的活动 1st

  Intent i = new Intent(FirstScreen.this, SecondScreen.class);   
String keyIdentifer  = null;
i.putExtra("STRING_I_NEED", strName);

活动二

 String newString;
if (savedInstanceState == null) {
    extras = getIntent().getExtras();
    if(extras == null) {
        newString= null;
    } else {
        newString= extras.getString("STRING_I_NEED");
    }
} else {
    newString= (String) savedInstanceState.getSerializable("STRING_I_NEED");
}

使用任何一种方式由你决定

于 2013-02-20T08:14:20.153 回答
1

您尚未将复选框添加到 cbs 列表中，并且您正在尝试从中访问复选框...

尝试通过 cbs.add(cb);在 for 循环中使用将复选框添加到列表...

试试这个

final List <CheckBox> cbs = new ArrayList<CheckBox>();

            for(int i = 0; i < 5; i++){
                CheckBox cb = new CheckBox(this);
                cb.setText("Apple" + (i + 1));
                cbs.add(cb);
                ll3.addView(cbs.get(i));
            }
于 2013-02-20T09:02:01.070 回答