如果集合对象中要用到contains方法或要比较两个对象要复写equals方法：
如下实体类：
public class DeviceInfo {
private String mDeviceName;//设备名
private String mDeviceMacAddr;//设备Mac地址
public DeviceInfo() {
// TODO Auto-generated constructor stub
}
public String getmDeviceName() {
return mDeviceName;
}
public void setmDeviceName(String mDeviceName) {
this.mDeviceName = mDeviceName;
}
public String getmDeviceMacAddr() {
return mDeviceMacAddr;
}
public void setmDeviceMacAddr(String mDeviceMacAddr) {
this.mDeviceMacAddr = mDeviceMacAddr;
}
@Override
public String toString() {
return "DeviceInfo [mDeviceName=" + mDeviceName + ", mDeviceMacAddr="
+ mDeviceMacAddr + "]";
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result
+ ((mDeviceMacAddr == null) ? 0 : mDeviceMacAddr.hashCode());
result = prime * result
+ ((mDeviceName == null) ? 0 : mDeviceName.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
DeviceInfo other = (DeviceInfo) obj;
if (mDeviceMacAddr == null) {
if (other.mDeviceMacAddr != null)
return false;
} else if (!mDeviceMacAddr.equals(other.mDeviceMacAddr))
return false;
if (mDeviceName == null) {
if (other.mDeviceName != null)
return false;
} else if (!mDeviceName.equals(other.mDeviceName))
return false;
return true;
}
}