Question

我有2项活动。 MainActivity和Screen2。我想在按下按钮到Screen2的同时从MainActivity发送在EditView中编写的文本，在那里的EditView上显示它。然后按下Screen2上的按钮，它需要将其返回到MainActivity并显示连接的消息。但我的应用程序一直在关闭，请帮助我

package com.example.car.cerdo;

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

public class MainActivity extends AppCompatActivity {
    String msg;
    public static final String Extra_Message = "myFirst";
    static final int Main_requestCode=1;
    TextView t = (TextView) findViewById(R.id.t1);
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button b = (Button) findViewById(R.id.b1);

        b.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent myIntent = new Intent(MainActivity.this, Screen2.class);

                msg = t.getText().toString();
                myIntent.putExtra(Extra_Message, msg);
                startActivityForResult(myIntent,Main_requestCode);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode==Main_requestCode)
        {
            String msg= data.getStringExtra(Screen2.Result_Message);
            t.setText(msg);
        }
    }
}
package com.example.car.cerdo;

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

public class Screen2 extends AppCompatActivity {
    String msg;
    public static final String Result_Message="my_Res";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_screen2);

        Intent i=getIntent();
        msg=i.getStringExtra(MainActivity.Extra_Message);
        TextView t= (TextView)findViewById(R.id.t2);

        t.setText(msg);
        Button b=(Button)findViewById(R.id.b2);
        b.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent resultIntent= new Intent();
                resultIntent.putExtra(Result_Message,  msg+" this is new");
                setResult(RESULT_OK,resultIntent);// REsultcode
                finish();
            }
        });

    }
}

编辑：在Mr.HHAR HUSSAIN＆＃39;答案之后已经纠正，问题仍然存在。我在评论部分的基础上添加了日志，请检查一下

Answer 1

在第一个活动中，在onActivityResult中，当您使用“my_res”字符串从第二个屏幕发送时，您正在使用“Result_Message”作为stirng接收字符串。而不是从Screen2调用变量，只需将变量名称放在字符串中以获得解决方案，请参阅下面的代码

在MainActivity.java中执行此操作：

@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if(requestCode==Main_requestCode) {
        String msg= data.getStringExtra(Screen2.Result_Message); 
        t.setText(msg);
    }
}

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1 个答案: