Question

我对android编程很新..我有这个问题..我想传递一个值，但结果是null ..我想知道为什么会这样..谁能帮助我？提前致谢。我的代码是这样的..

Manager.java

String prize="5";
Intent i = new Intent(Manager.this, Shop.class);
i.putExtra("Key", prize);
startActivity(i);

Shop.java

Intent myIntent = getIntent(); 
    String receive = myIntent.getStringExtra("Key");

    if (getIntent().getExtras() != null)
    {               
    TextView tv = (TextView)findViewById(R.id.textView2);
    tv.setText(receive);
    }

    else
    {
        TextView tv = (TextView)findViewById(R.id.textView2);
        tv.setText("value is null");  //this is always the result
                                       //why is it null??
    }

Answer 1

函数getExtras（）使用putExtras（b）返回放置在Intent中的Bundle。像这样：

Intent i = new Intent(Manager.this, Shop.class);
i.putExtras(new Bundle());
startActivity(i);

由于您没有使用putExtras函数，因此getIntent（）。getExtras（）返回null。你应该这样做：

Intent myIntent = getIntent(); 
String receive = myIntent.getStringExtra("Key");

if (receive != null)
{               
TextView tv = (TextView)findViewById(R.id.textView2);
tv.setText(receive);
}

else
{
    TextView tv = (TextView)findViewById(R.id.textView2);
    tv.setText("value is null");  //this is always the result
                                   //why is it null??
}

Answer 2

试试这个你试图访问你设置的不同键

String value= "Your String";
// Launching new Activity on selecting single List Item
Intent i = new Intent(getApplicationContext(), Test.class);
// sending data to new activity
i.putExtra("key", value);
startActivity(i);

在下一个活动中

Intent i = getIntent();
// getting attached intent data
String value= i.getStringExtra("value");
// displaying selected product name
txtProduct.setText(value);

Answer 3

试试这个：

getIntent().getExtras().getString("KEY");

可能应该这样做。

Android传递值为何null？

3 个答案: